The substitution reaction of benzyl chloride and sodium butyrate to form benzyl butyrate, using tetrabutyl ammonium bromide as the phase transfer catalyst (PTC) in a solid-liquid phase condition was studied. Benzyl chloride in solvent toluene forms the organic phase whereas sodium butyrate remains in solid form. A kinetic study of the system had been performed by varying different process variables. Different phase transfer catalysts were employed to find out the most effective catalyst. No conversion was found without catalyst.Homogeneous solubilisation mechanism was followed to explain the kinetic model and to interpret the experimental data.