This investigation is carried out in order to obtain a catalyst having excellent selectivity in the title reaction. The method of preparation of silica-alumina catalyst and the changes of alumina content indicated that there was no difference in the yield of picolines within the ranges of 12-29% by weight of Al2O3. Also, several of petroleum cracking catalysts gave nearly the same result. An addition of 5 % by weight of each of 15 kinds of heavy metal oxide to the. silica-alumina catalyst indicated that those of Ag, Fe, Co, Zn and Cd showed an increase in the yield of picolines, while Ag, V, Cu and Ni showed a tendency of formation of carbonaceous substance. In the catalysts with added Co, Zn, , and Cd, it was indicated that the yield of α- and γ-picolines was 24-29%, resp ectively, and that of high boiling pyrdines 9-14% of theoretical yield based on aldehyde, and the yield of total bases reached to 76%. Passing only α- or γ-picoline through the catalyst indicated that the polymerization, decomposition or isomerization to ?A-picoline of both picolines, did not occur and mutual rearrangement of them was only 0.60.8%.