Results of an experiment on the removal of cyanide from two industrial wastewaters by using gas-filled hollow fiber membranes in a pilot plant in China are presented. The plant was operated in batch mode using 1000L of feed solution. The plant contained 10 hollow fiber modules with a total effective membrane surface area of 180 m(2). The strip stream consisted of a 10% NaOH solution. The overall mass transfer coefficient for cyanide was determined experimentally. A decrease in the overall mass transfer coefficient with time was observed for real wastewaters due to fouling of the membrane. In particular, the presence of particulate matter in the wastewater can lead to a significant decrease in the overall mass transfer coefficient and, hence, the rate of cyanide removal. Various cleaning strategies were investigated in order to regenerate the membrane. The gas-filled membranes were stable for over two months of continuous operation when they were used with industrial wastewaters.