Arsinic acids are organoarsenic compounds with the formula R₂AsO₂H. They are formally, but not actually, related to arsinic acid, a hypothetical compound of the formula H₂AsO₂H. Arsinic acids are monoprotic, weak acids. They react with sodium sulfide to give the dithioarinates R₂AsS₂Na. Arsinic acids are related to phosphinic acids (R₂PO₂H.).

Well known arsinic acids include diphenylarsinic acid and cacodylic acid, R₂AsO₂H (R = Ph, Me, respectively).