The present investigation illustrates the application of mixed hydrotropy. A novel, safe and sensitive method of spectrophotometric estimation in the ultraviolet region has been developed using a mixed hydrotropic solution containing eight percent each of niacinamide, sodium acetate, sodium benzoate, sodium citrate and urea (total 40% hydrotropic agents), for the quantitative determination of hydrochlorothiazide, a very slightly water soluble diuretic drug in tablet dosage form. Beer's law was obeyed in the concentration range of 20–120 μg/ml. There was more than 25-fold enhancement in aqueous solubility of hydrochlorothiazide in mixed hydrotropic solution as compared with the solubility in distilled water precluding the use of organic solvents. Hydrotropic agents and commonly used tablet excipients did not interfere in spectrophotometric estimation. Results of the analysis were validated statistically and by recovery studies. Statistical data proved accuracy, reproducibility and the precision of the proposed method
