The reductive regeneration of a PdCaLaHY zeolite catalyst for isobutane alkylation with butylenes has been studied for the process carried out in the reaction-reductive regeneration-reaction mode. It has been found that the composition of regeneration products was identical to the alkylate composition, suggesting the proceeding of mild hydrocracking of hydrocarbon deposits on the catalyst surface. The optimal maximum temperature of catalyst regeneration has been determined using the TGA/DSC method. The catalyst regeneration conditions found to ensure almost complete recovery of the initial activity of the catalyst are as follows: a temperature up to 320A degrees C, pressure of 1.2 MPa, and a hydrogen space velocity of 1000 h(-1).