The reaction rate constants of the reaction of O,O＇-thiophosphoric acid esters with the general structure (RO)(2)P(S)SH (R = alkyl; subst. phenyl) with epoxidized native olis (rape oil, soybean oil, methyl ester of oleic acid) were determined with the aid of the reaction calorimetry. The reaction is 2. order and runs quickly with a small activation energy. Between the logarithm of the reaction rate constants and the characteristic Values of the initial products (acidity number - AZ, content of epoxidized linolenic acid - X(LDE)) exists a simple correlation of the type Ig k = a + b AZ + cX(LDE).