Mixtures of polar lipids were hydrogenated using the palladium-bis(alizarin monosulfonate) catalyst and the product mixtures were analyzed by MALDI-TOF mass spectrometry in order to determine the individual reactivity of the constituent lipids. In their binary mixtures, dioleyl phosphatidyl choline and dioleyl phosphatidyl ethanolamine showed the same reactivity. Addition of cholesterol slowed down the hydrogenation of these two lipids by about the same extent. Conversely, in the mixture of lipids isolated from the thylakoid of the blue-green alga Synechocystis PCC 6803, monogalactosyl and digalactosyl diacyl glycerols (MGDG and DGDG, respectively) reacted twice as fast as sulfolipids (SL) and phosphatidyl glycerol (PG).