The aim of this study was to develop and validate a method for determining phosphoryl trichloride in workplace air. The method is based on passing the tested air through a sodium carbonate-impregnated quartz fiber sampling filter. The substance collected on the sampling filter is extracted with ultrapure water. Phosphoryl trichloride is determined as chloride ions (the product of the hydrolysis of phosphoryl trichloride) in the obtained aqueous solutions by ion chromatography with conductometric detection. The developed method enables the determination of phosphoryl trichloride in the air in the concentration range from 0.004 to 0.160 mg/m3. The method is not applicable in the presence of phosphorus trichloride, hydrochloric acid, and its salts in the air. Good validation results were obtained. All requirements of the norm PN-EN 482 were met while developing and validating the method. This method can be used to measure workplace air in order to assess workers’ occupational exposure.