This review describes recent developments of size-, shape-, structure-and composition-dependent behavior of catalyst nanoparticles employed in alkylation, dehydrogenation, hydrogenation, and selective oxidation reactions for the conversion of hydrocarbons (with main emphasis on fossil resources) to chemicals. Innovation in these areas is largely driven by novel synthesis of (nano)porous and nanostructured catalytic materials. In case of alkylation, several new classes of porous materials have recently emerged as catalysts while the discovery of novel ultralarge-pore frameworks with desirable acidity remains largely a serendipitous process. Noble metal nanoparticles such as Pt, Pd, Rh, Au and their alloys with other metals have been extensively employed to catalyze a wide range of dehydrogenation, hydrogenation, and selective oxidation reactions of organic molecules. Novel approaches are still required to synthesize and characterize stable gold and other metal nanoparticles with tightly controlled sizes to further advance the knowledge of their unique size-dependent catalytic behavior. The bulk mixed metal oxides of vanadium, molybdenum, and other transition metals, such as the M I phase for propane ammoxidation to acrylonitrile, have shown great promise as highly active and selective oxidation catalysts. However, fundamental understanding of surface molecular structure-reactivity relationships of these systems remains highly limited. Future advances in all these areas may be possible through combined experimental and theoretical approaches. (C) 2008 Elsevier B.V. All rights reserved.