This paper describes the potential use of hollow fiber membranes in evaporative cooling applications for space air-conditioning. Duct-mountable hollow fiber membrane bundles and arrays are utilized as contactors for the delivery of liquid water to an air stream in a heating, ventilating air-conditioning duct. A series of experimental and analytical parametric studies are presented to assess the heat and mass transfer phenomena in evaporative cooling with hollow fiber membranes. The focus of the studies was to compare experimentally determined heat and mass transfer coefficients to estimates obtained from literature, to determine the influence of membrane and operating parameters on achievable mass and heat flux and to assess the efficacy of using hollow fiber membranes for evaporative cooling. The results point to a proof for the concept and further indicate that reasonable numbers of fibers and membrane surface area can provide cooling effectiveness comparable to conventional evaporative cooling equipment. (C) 2003 Elsevier B.V. All rights reserved.