A review with I I refs. covering the reactions and the processes (Fig. 1) of oxidation of cumene (1) with air and (I) cleavage of cumene hydroperoxide (11) (a 90% It solution containing 2-phenyt-2-propanol (111), acetophenone, and a-methylstyrene (IV)) with conc. H2SO4 at the acid and the II concentrations in the reaction mixture (60degreesC) of 0.1% and (1:30 w/w) 90% II-cleavage products, resp., and (H) in acetone as solvent. Process (H) offers a shorter reaction time and less by-products than does (1). Phenol tars (from decomposition of III, polymerization of IV, and condensation of IV with PhOH) can be (a) used to make phenol-formaldehyde resins, (b) coked and oxidized to yield coke and bituminous materials, (c) distilled to yield PhOH, acetophenone, cumylphenol, and IV, and (d) catalytically thermolyzed to yield PhOH and cumene. H2SO4 as catalyst and the resulting salts are environmentally disfavorable. Solid acid catalysts and middle- and large-pored beta-zeolites (e.g. ZSM-5), aluminosilicates, and montmorillonite clays treated with mineral acids, heteropolyacids or certain Lewis acids, are preferable but so far not applied practically.