Hydrogen sulphide removal in a waste water treatment plant at semi-industrial scale in a compact wet scrubber has been investigated. The gas residence time in the scrubber was reduced to 30 ms using a NaOCl caustic scrubbing solution. The contactor is composed of a wire mesh packing structure where liquid and gas flow co-currently at high velocity (>12 m s(-1)). H2S removal percentages higher than 95% could be achieved whereas a moderate pressure drop was measured (<4000 Pa). Both the hydrodynamic and chemical conditions can influence the efficiency of the process. Correlations were developed to predict both the pressure drop and the H2S removal efficiency at given operating conditions.