A quartz crystal microbalance (QCM) modified with a thin layer of standard gas chromatographic stationary phase of methyl phenyl silicon, 75% phenyl (OV25) was used to determine a number of chlorinated aliphatic hydrocarbons in atmospheric media. A solution casting method was used for modification of quartz crystal with a thin layer of OV25. Determination was based on the frequency shifts due to the adsorption of compounds at the surface of modified quartz crystal electrode. The frequency shifts were found to be linear against the concentration of analytes within the concentration range of 15-150mgl - 1 with the correlation coefficients of above 0.9910. The sensitivity factors in the range of 0.71-1.17Hz per mgl - 1 was obtained. Storage period of over 4 months proved no loss in sensitivity and performance of the sensor. Among some possible interferents tested (CO, CO 2 , NO 2 , O 2 and H 2 O), no major interference was involved in the performance of the sensor.