Thermoregulated phase-separable Ru-3(CO)(12)/PETPP (P-[p-C6H4O(CH2CH2O)(n)H](3), n = 6) complex was applied in the hydrogenation catalysis for the first time. With styrene as the model substrate, under the optimum conditions of P(H-2) = 2.0 MPa, T = 90 degreesC, the conversion of styrene and yield of ethylbenzene were 100 and 99.5%, respectively. After reaction, the catalyst could be easily separated from reaction mixture and reused for ten times without loss of activity has been observed. (C) 2002 Elsevier Science B.V. All rights reserved.