Various researchers have used infrared analysis to show that carbonyl compounds are produced during oxidation of asphalts (I-8). A controversy has developed about which functional types predominate. Knotserus (I-3) suggested that esters are the main type of oxygen containing products formed on oxidation of asphalts and that ketones, aldehydes and carboxylic acids are also produced, but to lesser extent. Campbell and Wright (5) disputed this conclusion and offered evidence based on the addition of model compounds to asphalts that carbonyl components in oxidized asphalts are mainly ketones, aldehydes and carboxylic acids. Knotnerus (1) estimated the amounts of carbonyl compounds in oxidized asphalt by oxime formation. The method was based on titration of the HCl liberated from hydroxylamine hydrochloride used to derivatize the carbonyl compounds. The method was complicated by the possible decomposition of hydroxylamine by metallic oxides and salts present in asphalts and by possible reaction with unknown functional groups. Peterson and coworkers in extensive research on carbonyl components in asphalts before and after oxidation (9-15) concluded that carboxylic acids, ketones, and dicarboxylic anhydrides were produced on oxidation via in-use or simulated aging. This article provides direct evidence for the formation of significant amounts of ketones on aging of asphalts. The presence of detectable amounts of aldehydes is discounted. The conclusions are based upon interpretation of infrared spectra of oxidized asphalts and their products resulting from sodium borohydride reduction and oxime formation.