The thermophysical properties (effective thermal conductivity k, permeability K, porosity x and effective specific heat C) of two types of monolithic activated carbons are investigated with the intention of designing a high performance generator for sorption refrigeration systems and heat pumps using ammonia as refrigerant. This paper is mainly focussed on the experimental results. Typical values obtained with one of the samples tested are: thermal conductivity = 0.44 W m(-1) K-1, limiting concentration = 0.36 kg NH3/kg carbon and carbon specific heat = 1080 J kg(-1) K-1 at 100 degrees C. The permeability results are highly anisotropic. (C) 2000 Elsevier Science Ltd. All rights reserved.