The concentrations of 17 carbonyl compounds were investigated in indoor air of two offices - one located in a green building and the other in an old building, both from Bucharest. Indoor air samples were collected during normal activities of the working staff on passive samplers. Two analytical techniques were used: Ion Chromatography for carboxylic acids and High Performance Liquid Chromatography for aldehydes and ketones. A questionnaire was administrated in order to collect information about buildings characteristics, indoor furniture, decorating materials and electronical devices used during the sampling. Formaldehyde, acroleine+acetone, acetaldehyde, hexaldehyde and carboxylic acids were the most abundant compounds that accounted for more than 50% of the total carbonyls. The majority of the aldehydes showed higher concentrations in the old building office compared to the concentrations found in the green building office. Regarding the carboxylic acids: the concentration of formic acid was slightly higher in the old building office versus the green building office; in the case of acetic acid, the concentration found in the old building office
was around two times higher comparing to the green building office.