Technical and procedural problems in measurements of the heats of chemisorption (CHS), including the urgency of generalization of the technical and procedural problems and the ways of their solution, specificity of calorimetric studies of CHS, design of the glass calorimetric ampoules and vacuum apparatuses for studies of CHS at powders, and approaches to extraction of information on the mechanisms of CHS and catalytic processes from CHS and calorimetric studies, are considered. The importance of data on the heats of CHS for solution of the "homogeneity" vs. "heterogeneity" problem is substantiated. The available results of adsorption and calorimetric studies of CHS at industrial catalysts approached to their states occurring under conditions of catalytic processes, the effect of improvement of the techniques and procedures, and numerous results of studies of the molar heats of CHS of CO, H-2, O-2, N-2, and hydrocarbons at metals and some oxides for about 60 gas-chemadsorbent systems are collected and discussed. It is concluded that surfaces reveal themselves as homogeneous. (c) 2009 Elsevier B.V. All rights reserved.