Abstract: The present invention discloses a composition of matter useful for insect repellency, which is topically applied in the form of a spray, liquid, cream, gel, ointment or towelette comprising a B vitamin, and in particular vitamin B1 (thiamine) in any chemical form, as the sole active ingredient or in combination with other active ingredients known to provide insect repellency. Such thiamine component of a final formulation is particularly effective when thiamine concentrations exceed 0.01% w/v in the topical mixture, and its use is preferred when concentrations are between 0.01 to 30% w/v thiamine. Said formulation is increased in effectiveness for insect repellency when additional ingredients are also added which are also known to provide insect repellency.