A spectrophotometric method is described for the determination of Nicoumalone and Acebutolol hydrochloride based on the formation of molecular complex with the reduction product of Nicoumalone or hydrolysis product of Acebutolol hydrochloride and p-N-methyl benzoquinone monoimine [formed in situ from metol (p-N-methylaminophenol sulfate) and potassium permanganate, PMBQMI] at pH 3.3. Quantitative measurements were made at the maximum absorption of 525 nm. Beer's law is obeyed in the range of 5-50-mu-g ml-1 and 5-60-mu-g ml-1 for Nicoumalone and Acebutolol hydrochloride respectively. The proposed method is comparable with the reference method when applied to pharmaceutical preparations, and tablets, An average percentage recovery of 99.5 +/- 0.8 was obtained.