The effect of additive NaOR (R = CH3, C2H5, C4H9) on the rate and selectivity of hydroformylation of allyl alcohol and propene in the presence of unmodified and modified triphenylphosphine rhodium catalysts has been shown. The dependence of the indices of hydroformylation on the ratios Na/Rh and PPh3/Rh and the nature of R and also the results of an IR spectral study of the catalytic complex indicate that the active Rh catalyst contains an OR group.