The objectives of the Third IUPAC Symposium on the Characterization of Porous Solids (COPS-III) were (1) to provide the opportunity for specialists to exchange ideas and new information on theoretical principles and methodology and (2) to generate proposals for the comparison and utilization of the many techniques now available for the characterization of porous solids. A successful outcome of the Symposium has been the final report of the IUPAC Subcommittee on Recommendations for the Characterization of Porous Solids, a summary of which is given in these proceedings. The edited papers included in the present volume have been selected from the 155 oral and poster presentations given at this symposium, which attracted 200 participants from 28 different countries. The following topics were discussed:1. Simulation and modelling of pore structures and pore-filling mechanisms2. Novel experimental techniques with particular reference to high-resolution techniques3. Model pore structures and reference materials4. Porous materials of technological importance.The wide range of materials and techniques described provide a useful and comprehensive reference source for academic and industrial scientists and technologists.