The modeling and analysis of electron devices including photovoltaic devices requires the knowledge of the surface recombination velocities at the two surfaces of the wafer along with the bulk lifetime. In this paper, the work of Luke and Cheng [J. Appl. Phys.61, 2282 (1987)] is extended to account for the asymmetric case of different surface recombination velocities at the two wafer surfaces. We present the analysis and discuss experimental procedures to extract the above three parameters. The contactless measurement technique is based on the transient behavior of infrared absorption due to the decay of optically excited excess carriers. In order to determine the surface recombination velocities at both surfaces, the measurements must be made with each side acting as the front surface. An example of parameter extraction is presented.