The properties of the wet channel surface in an indirect evaporating cooler, regarding its moisture wicking ability, diffusivity and evaporation ability, can greatly affect the cooling efficiency and performance of the cooler. Irregular fibres help to divert moisture and enlarge the wetted area, thus to promote evaporation. Ten different fabrics woven from various fibres were tested and compared. Coolmax® double pique fabric with the wicking height of 16.5cm, moisture diffused rate of 0.243cm2/s and natural evaporation rate of 2.86E-4g/s showed an excellent general performance. The Coolmax® double pique fabric attached onto an aluminium sheet to form a heat/mass exchanging wet channel wall of the indirect evaporative cooler, was experimentally studied for its moisture diffusivity and evaporation abilities. The results showed that this fabric had the great potential to improve the performance of indirect evaporative coolers.