An experimental investigation of porous ceramic evaporators for building cooling has been carried out. Prototypes, classified as low, medium and high porosity prototypes in direct evaporative cooling mode were placed in an experimental duct within an environmental chamber. Performance was measured under different conditions of dry bulb temperature (DBT), relative humidity (RH), supply water pressure. and layout within the duct. The high porosity ceramic evaporator consistently performed best, while increased water supply head also improved performance. Dry bulb temperature drops of 6-8 K have been achieved parallel with a 30% rise in relative humidity. Maximum cooling of 224 W/m(2) has been measured during test of the high porosity ceramic evaporator placed in a single row stack with water supplied at 1.0 m head. Empirical formulae relating mean cooling performance to [e(s) - e], the ambient to saturated vapour pressure difference have been derived. The direct evaporation of water into supply air using porous ceramic surfaces has demonstrated significant potential for building cooling. (C) 2003 Elsevier Science B.V. All rights reserved.