The regularities of mass transfer with a chemical reaction in the system of aqueous solution of sodium hydroxide (solid medium)/butyric acid (transportable component)/carbon tetrachloride (dispersed phase) in spray extractors are studied. It is shown that the resulting chemocapillary instability can significantly reduce the height of the transfer unit. The conditions for the occurrence of spontaneous concentration-capillary convection during mass transfer with a chemical reaction under conditions of constrained drop movement are determined.