A statistical experimental design was employed to study the effects of pressure, temperature, catalyst loading, and mixing speed on the solubilities (C*) and volumetric gas/liquid mass transfer coefficients (k(L)a) for H-2, N-2, CO, CH4 and C2H4 in a liquid mixture of hexanes containing iron oxide catalyst in a 4-litre agitated autoclave. Statistical correlations for k a values for the gases used were developed. Mixing speed and solid concentration showed the strongest effects on k(L)a. At low catalyst concentrations, a maximum in k(L)a was observed and at concentrations > 37 mass%, k(L)a decreased by more than one order of magnitude.