The authors have developed a passive cooling wall (PCW) constructed of a porous ceramics. The ceramics has a capillary force to soak up water and allow its vertical surface to be wet to a level higher than 1 m when its lower end is placed in water. The present paper describes experiments to investigate the developed ceramics performance and cooling effects of a prototype PCW constructed of the pipe-shaped ceramics. The following findings were understood from experimental data monitored in a summer period. Wet vertical surfaces of the ceramic pipe reached a height of more than 1 m. Surface wet conditions can be maintained throughout successive sunny days in the summer. It was found that there is a slight difference in vertical surface temperatures of the ceramic pipe on a sunny summer day. The air passing through the PCW was cooled and its temperature can be reduced by several degrees in the summer daytime. It was also found that surface temperatures of the shaded ceramic pipe can be kept at a temperature nearly equal to the wet-bulb temperature of outdoor air.