Abstract This study investigated the feasibility of generating humidity control porous ceramics by sintering a mixture of volcanic ash, weathered volcanic ash, and waste glass. The sintering conditions, including sintering time, sintering temperature, and various mixed portions of glass amendment, were tested. The final ceramics were analyzed for their pore distribution, pore volume, adsorption and desorption characteristics, and bending strength. The results indicate that the pore size of the volcanic ash ceramics tends to distribute in the range from 70 to 100 nm, whereas that of the weathered volcanic ash ceramics is in the range of 7–9 nm. The humidity controlling conditions of the ceramics take advantage of the inherent porosity of the natural materials. The bending strengths in both cases were all satisfying with the fractural intensity specification of ceramics (> 6 Mpa).