The objective of the present study was to select the optimal catalyst and operating conditions for the manufacture of C-9-alcohol, using C-9-aldehyde and hydrogen, in a trickle bed reactor. When CaO, Ce2O3 or MgO was added as a promoter to the Ni/kieselguhr catalyst, the BET and Ni surface areas were increased. In the reaction for the manufacture of C-9-alcohol, using C-9-aldehyde and hydrogen in a batch reactor, a Ni-MgO/kieselguhr catalyst showed the highest activity. In addition, the catalyst using Na2CO3 as a precipitant showed the highest activity. According to the result of an experiment to find the optimal reaction conditions for C-9-alcohol synthesis, using C-9-aldehyde and hydrogen in a trickle bed reactor loaded with Ni-MgO/kieselguhr catalyst, the highest yield of C-9-alcohol was 91.5 wt% at 130 degrees C, 400 psi and WHSV = 3. The C-9-aldehyde hydrogenation performance of the Ni-MgO/kieselguhr catalyst was similar to that of a Cu/ZnO/Al2O3 catalyst, but superior to that of Cu-Ni-Cr-Na/Al2O3 and Ni-Mo/Al2O3 catalysts. In a long-term catalysis test, the Ni-MgO/kieselguhr catalyst showed higher stability than the Cu/ZnO/Al2O3 catalyst. (C) 2007 Elsevier B.V. All rights reserved.