Cost efficiency is a state of optimal allocation of factors of production in which any other allocation will result to higher cost. In that case, the selection of farm inputs at minimum cost will help to reduce production cost and hence improve profitability of the farmers This research investigated the optimal allocation of factors of production by sorghum/cowpea intercrop farmers in Kebbi State Nigeria, with the aim of generating reliable information on their determinants. The technique applied in order to achieve the objectives of the study were the data envelopment analysis (DEA) and the ordinary least squares (OLS) regression. The data were obtained mainly from primary sources through a questionnaire survey of 256 monocroppers and intercroppers. Seventy-three sorghum/cowpea intercroppers were used for the cost efficiency analysis. The results show that the average cost efficiency of the sorghum/cowpea farmers in the study area was 0.52 indicating that the farmers were relatively cost inefficient. The result further indicated that years of farming experience and age of the farmer positively affected cost efficiency while access to credit and land fragmentation were found to decrease cost efficiency. Reduction in production cost through accessing support services such as subsidies on farm inputs, provision of credit, extension services and trainings on good agricultural practices by Government agricultural related and non-governmental agencies will also help farmers to apply the recommended farm inputs, which is also likely to influence cost efficiency positively. Farmers should also be sensitized on the benefits of having contiguous farms. This will lead to increase in the benefits from improving cost efficiency of the farmers in Kebbi State.