The purpose of this work is to synthesize the catalytic systems containing palladium nanoparticles and using hydroxycarbonates of yttrium and cerium as supports,and to test the catalytic activity of the obtained catalysts in the Suzuki cross-couping reaction.Nanocomposites Pd/Y(OH)CO 3 and Pd/Ce(OH)CO 3 were synthesized according to two methods:the first one-simultaneous production of nanoscale substrate and immobilization of palladium nanoparticles on its surface(nanocomposites 1),the second one-the prior synthesis of polyvinylpyrrolidone stabilized palladium nanoparticles followed by their immobilization on the nano sized substrate surface(nanocomposites 2).The reaction between phenylboronic acid and iodobenzene is chosen as a model one.The dependence of the catalytic activity of catalysts on the method of their synthesis was established.It was established that nanocomposites 2 exhibit higher catalytic activity in the selected reaction compared to the nanocomposites 1.The TOF values for the nanocomposites 1 are 6663～14617 h 1 when using the substrate Ce(OH)CO 3 and 13774～27084 h 1 when using the substrate Y(OH)CO 3,while the nanocomposites 2 reveal TOF = 87287 h 1 for the substrate Ce(OH)CO 3 and TOF = 97746 h 1 for the substrate Y(OH)CO 3 under other equal conditions.In addition,nanocomposites 2 “work” at room temperature giving a high yield of the desired product.It is noted that the support nanoparticles Y(OH)CO 3 and Ce(OH)CO 3 also exhibit catalytic activity.The yield of the final product of the reaction using them as catalysts is 55%(TOF = 11 and 8 h 1,respectively).Thus,the use of yttrium and cerium hydroxycarbonates as supports allows to decrease the palladium content in the nanocomposites to 0.01%～1% and,consequently,reduce the cost of the catalyst while maintaining its high catalytic activity. The purpose of this work is to synthesize the catalytic systems containing palladium nanoparticles and using hydroxycarbonates of yttrium and cerium as supports, and to test the catalytic activity of the obtained catalysts in the Suzuki cross-couping reaction. Nanocomposites Pd / Y (OH) CO 3 and Pd / Ce (OH) CO 3 were synthesized according to two methods: the first one-simultaneous production of nanoscale substrate and immobilization of palladium nanoparticles on its surface (nanocomposites 1), the second one-the prior synthesis of polyvinylpyrrolidone stabilized palladium nanoparticles followed by their immobilization on the nano sized substrate surface (nanocomposites 2). The reaction between phenylboronic acid and iodobenzene is chosen as a model one. The dependence of the catalytic activity of catalysts on the method of their synthesis was established. It was established that nanocomposites 2 exhibit higher catalytic activity in the selected reaction compared to the nanocomposites 1. The TOF values for the nanocomposites 1 are 6663-14617 h 1 when using the substrate Ce (OH) CO 3 and 13774-27084 h 1 when using the substrate Y (OH) CO 3 while the nanocomposites 2 reveals TOF = 87287 h 1 for the substrate Ce (OH) CO 3 and TOF = 97746 h 1 for the substrate Y (OH) CO 3 under other equal conditions. In addition, nanocomposites 2 “work ” at room temperature giving a high yield of the desired product. It is noted that the support nanoparticles Y (OH) CO 3 and Ce (OH) CO 3 also exhibit catalytic activity. The yield of the final product of the reaction using them as catalysts is 55% (TOF = 11 and 8 h 1, respectively) .Thus, the use of yttrium and cerium hydroxycarbonates as supports allows to reduce the palladium content in the nanocomposites to 0.01% ~ 1% and, therefore, reduce the cost of the catalyst while maintaining its high catalytic activity.