<jats:title>Abstract</jats:title><jats:p>A simple, rapid, accurate and reproducible reverse‐phase HPLC method has been developed for simultaneous identification and quantification of three coumarinolignoids, cleomiscosin A (Cliv A), cleomiscosin B (Cliv B) and cleomiscosin C (Cliv C) in different extracts of the seeds of <jats:italic>Cleome viscosa</jats:italic> using photodiode array detection at 326 nm. Cliv A, B and C were separated on a Waters symmetry C<jats:sub>18</jats:sub> column (250 × 4.6 mm, 5 μm) using the solvent system consisting of a mixture of acetonitrile : methanol (1:2 v/v) and water : acetic acid (99.5:0.5 v/v) as a mobile phase in a gradient elution mode. The calibration curves were linear in the concentration ranges 15–200, 10–80 and 15–180 μg/mL for Cliv A, Cliv B and Cliv C, respectively. The limits of detection and quantification for Cliv A, Cliv B and Cliv C were 15 and 20 μg/mL, 10 and 15 μg/mL and 15 and 20 μg/mL, respectively. The intra‐day and inter‐day precisions were 2.08 and 0.93% for Cliv A , 1.22 and 0.39% for Cliv B and 1.29 and 0.23 for Cliv C respectively. The developed HPLC method was used to identify and quantify Cliv A, Cliv B and Cliv C in different extracts of seed of <jats:italic>Cleome viscosa</jats:italic>. Copyright © 2010 John Wiley & Sons, Ltd.