Axial mixing in a novel pilot scale landau reciprocating plate column (LRPC) has been investigated for counter-current gas-liquid contacting over a wide range of operating conditions. The experimental results obtained using the dynamic response method were analysed using both the dispersion and compartment models under different boundary conditions and using both the method of moments and the direct time domain parameter estimation techniques. Based on the results, it was identified that axial mixing in this column can be best described using the back flow and the dispersion models solved with "closed-closed" boundary conditions. A general correlation describing the effect of operating parameters on the extent of axial mixing was developed with a mean absolute relative residuals of 6.8%. Similar to other RPC designs, axial mixing in LRPC increases with increasing both phase flows and plates oscillatory velocity. Values of axial dispersion coefficient in this work ranged from similar to 10(-4) to over similar to 3 x 10(-3) m(2)/s, which are comparable or less than those in other RPC designs under similar phase velocities and oscillatory conditions, but an almost order of magnitude lower than those measured in bubble columns under similar operating flow rates. (c) 2005 Published by Elsevier B.V.