A method has been developed and validated for the collection of the propylene glycol butyl ether esters of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in air and their determination by gas chromatography with electron capture detection. The samples are collected on XAD-2 resin, desorbed in diethyl ether prior to analysis. The procedure is designed for industrial hygiene monitoring to provide an accurate 4 hour time-weighted average of the exposure level. Recoveries were found to be 97±8% (2σ) for the propylene glycol butyl ether esters of 2,4,5-T in the concentration range of 0.70 ppb (v/v) to 5.00 ppm (v/v). Breakthrough concentrations, storage effects and humidity effects were also investigated.