A field experiment was conducted to evaluate potassium salt of glyphosate (MON 76366) in Roundup Ready Bt cotton hybrid at PAU, Ludhiana during 2009 and 2010. Potassium salt of glyphosate 50 EC at 900, 1350, 1800, 2700, 3600 and 5400 g/ha was applied twice (after one and three months of sowing) as post-emergence. All the treatments except glyphosate 900 g/ha and weedy check gave effective control of weeds. Application of K salt of glyphosate at 1350 to 5400 g/ha recorded the weed control efficiency (WCE) ranging from 96.8 -99.8%, and produced higher seed cotton yield. The performance of succeeding crops of wheat, barley and raya sown after cotton was not affected, indicating no residual toxicity of K-salt of glyphosate.