The recombinant expression and purification of viral proteins are a key component in the study of the immune response of viruses, as well as the creation of diagnostic techniques for the detection of viruses. For structurally simple proteins, one commonly used technique is the production of recombinant proteins in bacterial expression systems, which enable the large-scale synthesis and purification of recombinant viral proteins. In this technique, the cDNA encoding for a viral protein is cloned into a bacterial expression vector (with an appropriate purification tag), produced in a modified bacterial culture, and optimized for maximum protein production in a minimal amount of time. In this chapter, a protocol for the production of Rift Valley fever virus nucleoprotein is described. This protein has been previously shown to highly antigenic (and thus, is used in diagnostic tests), and has also been shown to be a potent inducer of the T-cell response following Rift Valley fever virus infection. The protocol outlined in this chapter describes the cloning of the cDNA of RVFV nucleoprotein into a bacterial expression vector, which also contains a fusion protein for optimal protein expression and solubilization, as well as a poly-histidine tag for efficient purification This chapter also describes the steps required for bacterial transformation, culture, lysis, purification and dialysis of RVFV nucleoprotein, resulting in a recombinant protein preparation, which can be upscaled to produce milligram quantities of protein product, which in turn can be used for downstream immunological and diagnostic applications.