Carbortylation of benzyl alcohol to phenylacetic acid in the presence of RhCl3 was studied. The influence of iodine-containing promoters and some reaction parameters on the catalytic properties of rhodium complexes was examined. It was found that carbonylation in the presence of benzyl chloride as a coreactant and potassium iodide as a promoter led to a considerable increase in the acid yield and allowed the reaction temperature to be lowered. It was established that the carbonylation of benzyl alcohol proceeded analogously to methanol carbonylation in the presence of the Rh/I catalyst system, and the actual promoter was benzyl iodide produced in the exchange reaction of benzyl chloride with KI. The use of chitosan as a polymeric support in this reaction was shown to have promise because it not only stabilized catalytically active species but also made it possible to increase the reaction selectivity even at high temperatures.