As known, glycerol, one of the products from reversible transesterification of alcohol with glycerides, drives the reaction backward. This work focuses on the effects of glycerol in the reaction with image analysis. The experiments were done by using various alcohols and refined palm oil (molar ratio of 6:1) with sodium methoxide catalyst (0.6% w/w oil) at 60 oC for 10 minutes. Amounts of glycerol and order of mixing glycerol with oil or alcohol were studied. Results show that the glycerol amount estimated from image analysis is mostly compatible with titration determinations. Image analysis shows that glycerol dissolves well in methanol and yields less generated glycerol. The different alcohols give different amounts of glycerol. Longer reaction time gives more and larger glycerol drops, which slows down the mass transfer rate of transesterification and induces the reaction to pseudoequilibrium.