The complexation equi;ibria between norfloxacin (NOR), ciprofloxacin (CIP) and ofloxacine (OFL) with tungstate, molybdate and vanadate have been studied by conductometric, potentiometric and spectrophotometric methods. The 1 :1 ion associatation complex formed in solution and their stability constanrs were calculated by potentiometric and spectrophotometric methods at 25 ± 2 ºC. the complexes formed at the optimum conditions obyed Beer`s law within the range 0.2 – 12.0 µg mL-1. The molar absorptivity and Sandell sensitivity are also calculated, and the interference from the common additives or excipients has been studied. The results showed recovery of 99.7 ±0.9 %, with RSD below 1.4 %. The proposed method was successfully applied to the determination of the drug in pharmaceutical formulatioins. A good precision and no significance difference with the results obtained by the official methods are demonstrated via t- and F- values Quim. Anal., 20, 37–45 (2001).