In sorghum, male sterility has been induced mainly using mechanical and genetic means with minimal use of chemical methods. Mechanical sterility induction is limited to producing small quantities of seed and genetic male sterility is limited to specific germplasm. An effective chemical hybridizing agent could be used to produce large amounts of seed and would not be limited by genotypes. The chemical trifluoromethanesulfonamide (TFMSA) was evaluated as a male gametocide in sorghum. In greenhouse conditions, TFMSA induced varying degrees of male sterility contingent on the dosage, timing of application, and sorghum genotype. If applied at or after the flag leaf emergence, panicles were male fertile but male sterile when applied at least 2d before the flag leaf emerged. In terms of dosage, 2mg of TFMSA rendered a BTx623 male sterile if applied 26d prior to flag leaf emergence. However, 30mg of TFMSA applied as much as 34d before the flag leaf emerged also induced complete sterility of the panicle. There may be a genotypic effect as less TFMSA was necessary to induce complete male sterility in BTx623 than in BTxArg-1. No phytotoxic effects or reductions in female fertility were observed in dosages of TFMSA up to 40mg. Germination of hybrid seed made on treated plants was equal to that of the parents and the hybrid seedlings were phenotypically normal. The results indicate that male sterility can be induced effectively in sorghum using TFMSA at appropriate dosages and application timings.