Molten carbonate fuel cells (MCFC) are the systems suitable for large-scale energy production. The cathode material used in these cells is NiO. In this study the NiO cathode was synthesized by tape-casting method and the adsorption of CO2, one of the cathode feeding gases, was investigated on it. The adsorption studies were carried out by the use of packed column and the adsorption analysis were performed using pulse response technique. There were two 1/4 in. diameter and 5 and 10 cm length columns prepared for the experiments and they were packed with 3 mm average particle sized NiO. The experiments were carried out with gas chromatography using He as a carrier gas. The response curves were taken after pulsing the columns with CO2. The equilibrium constants and heat of adsorption of CO2 on NiO were determined by the use of the first absolute moment equations corresponding to retention times. It was observed that the adsorption was physical in nature. From the adsorption constants determined at different temperatures and the heat of adsorption, DeltaH(0), was found as -1299 cal mol(-1). (C) 2004 Elsevier B.V. All rights reserved.