The kinetics of photo-isomerization and photo-degradation of 2-hydroxy-5-methylbenzophenone (E)- and (Z)-oximes in ethanol, octane, toluene and a mixture of octane and toluene under exposure to UV light was studied. The products of the photo-isomerization/photo-degradation of both oximes are similar but the conversion rate and amount of photo-degradation products of 2-hydroxy-5-methylbenzophenone (Z)-oxime are much higher. Also the photodegradation of the (Z)-isomer is quicker than its photo-isomerization to the (E)-isomer. The photo-isomerization and photo-degradation kinetic models were developed for both oximes. The formulated kinetic model contains 12 reaction rate constants which have been estimated from experimental data. Good agreement was found between experimental and predicted data.