Heterogeneous catalysis of transfer reduction was assessed by measurement of liquid-phase adsorption isotherms, enabling quantitative evaluation of H-donor, H-acceptor and solvent interplay at the catalyst surface so as to find the optimum reaction conditions. Liquid-phase isotherms were measured for adsorption of aromatic aldehydes (H-acceptors) onto a commercial Pd/C catalyst from a range of solvents. The resulting isotherms provided fundamental information on the competitive adsorption of aldehyde and solvent molecules at sites on the catalyst surface. These results suggested a novel solvent system for the heterogeneously catalysed transfer reduction of aromatic aldehydes to alcohols. This new solvent system performs heterogeneously catalysed transfer reduction of aromatic aldehydes at room temperature in a highly selective way, thus, avoiding the previously proposed unselective processes requiring high temperatures. The heterogeneous catalyst was re-usable at least five times without any loss of activity. A major role of oxygen as a reverting inhibitor of transfer reduction was demonstrated. (c) 2005 Elsevier B.V. All rights reserved.