A field experiment was conducted at the Norman E. Borlaug Crop Research Center, Pantnagar, during the rainy seasons of 2009 and 2010  to evaluate the efficacy of tembotrione (42% SC), a new post-emergence herbicide against mixed flora in maize as well as its residual effect on growth and yield of the succeeding mustard crop. The experimental field was highly infested with Echinochloa colona, Digitaria sanguinalis and Cyperus rotundus. Post emergence application of tembotrione 120 g/ha along with surfactant was found most effective to control the grassy as well as non-grassy weeds as compared to other herbicidal treatments either applied as pre or post emergence. This treatment also recorded highest grain yield during both the years which was at par with a lower dose (110 g/ha + surfactant) or even pre emergence application of the herbicide. Addition of surfactant (1000 ml/ha) increased the kernel yield significantly and reduced the density of weeds effectively as compared to the application of tembotrione without surfactant. No residual effects were observed on the growth and yield of succeeding mustard crop.