A liquid scintillation spectrometry method for the determination of 234Th in seawater with 230Th as the yield tracer has been developed and validated. 234Th is separated from the dissolved phase by an Fe(OH)3 precipitation and is then purified using ion exchange chromatography. The counting source is prepared by taking the sample to dryness in a vial, redissolving in acid, and mixing with a scintillation cocktail. The instrument employed has a relatively low background (11 cpm) and the ability to separate α from β activity on the basis of pulse shapes. The 234Th + 234mPa counting efficiency is 50% over the counting window employed. The limit of detection, using the above parameters, a 20 L sample, and a 400 min count is found to be 0.04 dpm L-1. It was also demonstrated that less advanced instruments, without α/β separation, can also be used effectively.