Cinnamate was investigated at different percentage of aqua-organic solvent mixture with Acetone (30 to 70% v/v) over the temperature range of 20o C to 40 o C. The specific rate constant was found to be decreased with increasing proportion of solvent (Acetone) at all the temperature range. The Iso-composition Activation energy (EC) was also evaluated which decreases with solvent composition in (water-Acetone) system. The number of water molecule associated with the activated complex is found to be increase (0.7003to 0.786) in water-Acetone system. The Thermodynamic Activation Parameter such