Reaction between phenylfluornne .lerivative- (4.5- dibromo-phenyl fluoronr) and antimony has been investigated, and optimun analytical conditions were given. The effects of thirty ele-meats and some masking agents for the determination of antimony were tested. When amounts of titanium, niobium, bismuth and germanium are higher, antimony can be determined in 6 N sulphuric acid. but molybdenum interfere seriously. The standard deviation is 0.0043%.coeficieat of variation is 6.2%for 11 determinations of 0.06-0.07% of Antimony.