on (one) of the most/least/...

The short rule: after "one of the" you should follow a plural noun or noun phrase. Never insert another "one" after "of"-that creates redundancy and a number mismatch.

Below: a clear rule, why learners add the extra "one", many wrong→right pairs, real-world examples, step-by-step rewrites, quick memory tricks, and related mistakes to watch for.

Quick answer

Say "one of the most/least/best + [plural noun]". Do not write "one of the one most..." or "one of the most one...".

Correct: She is one of the most talented singers.
Incorrect: She is one of the one most talented singers.
Check: the word after the superlative should name a group (singers, books, ideas), not repeat "one".

Core rule (plain and simple)

Structure: one of the + superlative/comparative phrase + plural noun. "One of the..." picks a single item from a group, so the group must be plural.

Correct: "one of the most successful companies" - group = companies (plural).
Incorrect: "one of the most successful company" - company is singular.
Never insert a redundant "one" after "of".

Pattern: Correct: He is one of the most experienced engineers on the team.
Wrong-pattern: Incorrect: He is one of the one most experienced engineers on the team.

Why learners add the extra 'one'

Common causes: speaking in chunks, interference from phrases like "the one", and trying to force emphasis on singularity. Writers often mix two constructions: "one of the [plural]" and "the one [singular]".

Speech pause: "one" + pause + "of the most..." can become "one of the one..." when written quickly.
Interference: confusing "the one who" with "one of the who/which".
Editing under pressure leads to redundant words slipping in.

A quick grammar note

"One of the" is a quantifier selecting a single member from a set. After a superlative like "most/least/best", the head noun stays plural.

If you need to emphasize the single item, use a different structure: "the only one", "the one", or "one particular".

Correct: "one of the best ideas" (best + ideas - plural).
Alternative: "the only one that matters" (different meaning and emphasis).

Why a sentence-level checker helps

Spellcheck may miss quantifier-noun mismatches. A sentence-level checker spots when "one of the" is followed by an impossible singular phrase and suggests natural rewrites.

Soft tip: A context-aware tool can flag "one of the one" and offer fixes without changing your tone.

Spacing & hyphenation note

This mistake is about inserting a word, not about hyphenation. Keep the phrase as separate words: "one of the most".

Wrong forms to avoid: "one-of-the-most", "one of the-most".
Correct spacing: "one of the most".

Real sentences - work, school, casual

Short wrong→right examples in typical contexts.

Work - wrong: She's one of the one most reliable people on the project.
Work - right: She's one of the most reliable people on the project.
Work-wrong2: This report is one of the one best documents we've produced.
Work-right2: This report is one of the best documents we've produced.
School - wrong: That proof is one of the one clearest examples in the lecture.
School - right: That proof is one of the clearest examples in the lecture.
School-wrong2: This essay is one of the one strongest submissions this semester.
School-right2: This essay is one of the strongest submissions this semester.
Casual - wrong: That was one of the one funniest nights I've had.
Casual - right: That was one of the funniest nights I've had.
Casual-wrong2: This is one of the one least stressful weekends ever.
Casual-right2: This is one of the least stressful weekends ever.

Try your own sentence

Test the whole sentence rather than the phrase alone. Context usually reveals whether the noun should be plural.

Quick wrong → right pairs you can copy

Six compact pairs. Copy the correct forms into your drafts.

Pair1: Wrong: He is one of the one tallest players on the team.
Right: He is one of the tallest players on the team.
Pair2: Wrong: This is one of the one biggest mistakes we've made.
Right: This is one of the biggest mistakes we've made.
Pair3: Wrong: She's one of the one most successful entrepreneurs I know.
Right: She's one of the most successful entrepreneurs I know.
Pair4: Wrong: One of the one least expensive options failed the test.
Right: One of the least expensive options failed the test.
Pair5: Wrong: That book is one of the one most influential in the field.
Right: That book is one of the most influential in the field.
Pair6: Wrong: One of the one best answers came from the intern.
Right: One of the best answers came from the intern.

How to fix your sentence (step-by-step rewrites)

Three practical rewrites: remove the extra word, check plural agreement, and, if needed, rephrase for clarity.

Step 1: Remove the extra "one" between "of" and the superlative.
Step 2: Make sure the noun after "most/least/..." is plural.
Step 3 (optional): If it still sounds awkward, use "among" or restructure the sentence.

Rewrite1: Original: She is one of the one highest-rated candidates. Direct fix: She is one of the highest-rated candidates. Natural
alternative: She ranks among the highest-rated candidates.
Rewrite2: Original: That was one of the one strangest experiences I've had. Direct fix: That was one of the strangest experiences I've had. Natural
alternative: It was among the strangest experiences I've had.
Rewrite3: Original: This is one of the one most important tasks tonight. Direct fix: This is one of the most important tasks tonight. Natural
alternative: This is one of tonight's most important tasks.

Memory tricks & quick checks

Two quick proofreading checks to catch the error fast.

Ask: "Is the thing after this a group (plural)?" If not, it's likely wrong.
Read the phrase aloud: an extra "one" after "one of the" will sound like a stutter.

Mnemonic: Think "one of the crowd" - "of the" introduces the crowd (plural); you're picking a single member from it.

Similar mistakes to watch for

Fixing this error can expose related slips. Watch for number agreement and confusion between "one of the only" and "the only one."

"one of my favorite(s)" - when naming items, use the plural: "one of my favorite books".
"one of the only" vs "the only one" - they carry different meanings; choose based on intent.
Avoid inserting repeated determiners like "the" twice or other redundant words.

Similar1: Wrong: He is the only one of the best candidates.
Right: He is one of the best candidates. / He is the only one who met the criteria.
Similar2: Wrong: One of my favorite is this song.
Right: One of my favorite songs is this song.

FAQ

Is "one of the most" always followed by a plural noun?

Yes. The phrase selects one item from a group, so the noun after the superlative should be plural (e.g., "one of the most interesting books").

Can I ever say "one of the one ..." for emphasis?

No. That phrasing is ungrammatical. Use "the only one" or "one particular" to stress singularity.

What about "one of my favorite" vs "one of my favorites"?

Both appear in usage, but when you name the items, prefer the plural: "one of my favorite books." If you use "favorite" as a noun, "favorites" is common: "one of my favorites."

How can I find all occurrences of this mistake in a long document?

Search for "one of the one" or scan for "one of the" followed by "one" or a singular noun. A sentence-level grammar checker can flag mismatches between quantifiers and noun number.

Is this error common in speech too?

It appears more in writing than careful speech. Hesitation or mis-hearing can cause it to show up in drafts; proofreading usually catches it.

Quick tip before you hit send

Scan for "one of the" and check the immediate next word. If it's "one" or a singular noun, pause and fix it. For a fast, context-aware check, paste the sentence into a grammar tool that flags number mismatches and suggests rewrites.