Plant receptor kinases play diverse signaling roles in disease resistance and plant development. They represent a large plant gene family with over 600 members in Arabidopsis thaliana. While the functions of several members of the receptor kinase family have now been elucidated, a great proportion still remains uncharacterized. The structural and functional characterization of such plant receptor kinases may entail biochemical approaches that require access to purified protein, which can be made possible through heterologous protein expression. This chapter describes a strategy for expressing plant receptor kinases in E. coli, a bacterial host that has successfully been used to express and purify certain plant receptor kinase domains, some of which were subsequently used for biochemical assays. As full-length receptor-like kinases may be difficult to express, it is suggested to clone and express domains separately, after having identified domain borders using bioinformatics tools. A detailed cloning protocol is provided, as well as advice for testing expression efficiency and handling of expressed protein ending up in inclusion bodies.