Various conditions and several kinetic behaviors of the aldol condensation reaction of propanal (PA) catalyzed by the amino group of glycine (Gly) have been investigated. The rate of Gly consumption during the reaction of PA-Gly system was fairly slow. The rate of disappearance of PA was in a first order term with respect to the initial concentration of PA, and that of 2-methyl-2-pentenal (MP) which was the condensation product of PA was very slow, suggesting poor reactivity of MP. An activation energy of 10.9 kcal/mole was calculated. It is deduced from the rate expression of MP formation, d[MP]/dt=k[Gly][PA]1.1∼1.2. The rate of the reaction was little affected by ionic strength in its range from 0.15 to 1.15.