This paper presents the results of a comparative numerical investigation on packed bed thermal models suitable for sensible and latent heat thermal storage systems. Four basic groups of models were investigated, that is, the continuous solid phase models, Schumann's model, the single phase models and the thermal diffusion models or models with thermal gradient inside the particles. For each of these models a computer code was written and optimized. The models were first evaluated in relation to the computational time consumed to solve a specific test problem. The models were then compared in relation to the influence of particle size, void fraction, particle material, flow rate variations, working fluid inlet temperature variations and finally wall thermal losses. The results obtained were compared, analysed and discussed (C) 1999 Elsevier Science Ltd. All rights reserved.197757788