A new spectrophotometric method based on the oxidation reaction between iodide and iodate in the presence of the carboxylic acid form of losartan potassium (LP) was developed for the estimation of LP in pharmaceutical products. HPLC/MS method, kinetic studies and central composite design method were used for formation reactions, equilibration and determination of stability time and experimental conditions, respectively. The developed spectrophotometric method was validated. The equilibration period was calculated to be 10 minutes. 0.05 M KI and 0.003 M KIO3 and the quantity was calculated as 1.953 ml (0.0195 M) and 1.961 ml (0.00117 M), respectively; and the measured temperature was 32.3°C. The method was revealed to be linear between 4 and 30 μg/mL with a correlation coefficient of 0.9996. The LOD and LOQ parameters were calculated as 0.61 and 1.85 μg/mL, respectively. The pharmaceutical preparations were analyzed by the developed kinetic spectrophotometric method. The results obtained ranged between 94.9% and 100.9%.Keywords: losartan potassium, central composite design, spectrophotometric methodHypertension, an important and independent risk factor for cardiovascular disease, is best managed by maintaining blood pressure at -above 140/90 mmHg[1]. Angiotensin II receptors, many receptor antagonists are blocking receptors that control blood pressure [2]. The newer member of antihypertensive agents called angiotensin II receptor antagonists has no significant side effects [3]. Losartan potassium (LP) is the first angiotensin II receptor antagonist and is used chemically as an antihypertensive agent that specifically blocks the angiotensin II type 1 receptor [4]. Simple and rapid analysis methods must be developed...... middle of article ..... .d reported in the literature[26]. LP was also one of the drugs of the sartan group including the mentioned functional group. But the oxidation reaction between IO3 and LP has not been studied yet. Thus, the aim of this work was to develop, optimize and validate a new specific, precise and sensitive spectrophotometric method based on the oxidation reaction between iodide and iodate in the presence of carboxylic acid in the form of LP giving a yellow colored product. (λmax = 286 nm) to determine LP in pharmaceutical tablets. Optimization of reaction conditions was carried out by applying response surface methodology based on central composite design which saves time and effort through estimation of optimal conditions. In addition, the kinetic study of the reaction was carried out to avoid interference from the colored background and/or turbidity of the samples...