Field investigations were carried out at wetland farm, Agriculture College and Research Institute, Tamil Nadu Agricultural University, Coimbatore, during rainy seasons (June to October) of 2014 and 2015 to evaluate penoxsulam on weed control and yield of rice and its residual effect on microorganisms and succeeding greengram crop. Two years of field experimentation, revealed that pre-emergence application of penoxsulam at 22.5 g/ha resulted in significantly lower total weed density, weed biomass and higher weed control efficiency at all the stages. Application of new formulation of penoxsulam (21.7% SC) at 22.5 g/ha as pre-emergence herbicide kept the weed density and biomass below the economic threshold level and increased the grain yield as 5.20 and 5.04 t/ha in 2014 and 2015, respectively in rice. Succeeding greengram crop sown immediately after the rice harvest was not affected by the residue of new formulation of penoxsulam at all tested doses.