Cambridge Learner’s Dictionary records interested in + -ing for wanting or considering an activity and also interested + to-infinitive in uses such as being interested to find something out. The choice is therefore meaning-sensitive rather than a simple right-versus-wrong contrast.
ReviewedEvidence1 sourceSectionEnglish Usage
Quick answer
Both can be grammatical, but they usually do different jobs: “interested in doing” expresses interest in an activity, while “interested to learn/see/hear” often expresses attention or reaction to information.
Key details
Confusion Familygrammar-and-usage distinction
Rule Familypreposition and verb-complement pattern
TermsBe Interested In Doing, Be Interested To Do
Further guidance
Boundary
The infinitive pattern is not freely interchangeable with interested in + -ing. Check the intended meaning and the lexical context instead of mechanically replacing one form with the other.
Construction
Use interested in + -ing for interest in an activity or possibility; use interested + to-infinitive in established contexts where the infinitive expresses what one is curious, willing, or attentive to learn, see, hear, or discover.
Decision
Both can be grammatical, but they usually do different jobs: “interested in doing” expresses interest in an activity, while “interested to learn/see/hear” often expresses attention or reaction to information.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
Cambridge records “accuse someone of something” and specifically “accuse someone of doing something.” That supports of + -ing when the action is the alleged wrongdoing.
Cambridge records accustomed to something and gives -ing examples such as being accustomed to working or being treated in a particular way. Do not interpret the “to” after accustomed as an infinitive marker in this construction.
Cambridge distinguishes adapt to a situation or activity from transitive patterns such as adapting plans to fit new circumstances. The surface sequence “adapt … to + verb” therefore needs its grammatical structure identified before choosing an -ing form or infinitive.
Cambridge distinguishes “apologize to someone” from “apologize for something/doing something.” You can combine the two roles, as in “apologize to someone for doing something”; “to” marks the recipient while “for” marks the reason.
Cambridge distinguishes intransitive “approve of” for a favorable opinion from transitive “approve something” for official acceptance or authorization. The official-authorization sense uses transitive “approve” with an object; do not collapse that separate sense into the “approve of doing” judgment pattern.
Oxford documents the person-action pattern as be banned + from + -ing and separately documents direct-object uses of ban. The cited evidence does not support person + to-infinitive as the equivalent prohibition construction.
