The performance of the AnalystÒ passive sampler for the measurement of formaldehyde and acetaldehyde was assessed in a series of field experiments. It consists of a polyethylene cylinder filled with silica gel or a FlorisilÒ adsorbent and a stainless steel or a silver anti-turbulence net which works as an ozone scrubber. Indoor and outdoor formaldehyde and acetaldehyde concentrations were measured in different locations (offices and rooms of a public building, a car, laboratories and private homes) of Ciudad Real (Spain) and Rome (Italy). In some cases, RadielloÒ passive samplers were used along with AnalystÒ, in order to compare and validate the results. The performance of the AnalystÒ device was also assessed by checking some parameters such as the diffusive sampling rate of acetaldehyde and the storage stability after collection and the self-consistency for both formaldehyde and acetaldehyde. From this work, it can be concluded that the AnalystÒ sampler is suitable for measuring formaldehyde and acetaldehyde in indoor and outdoor air.