Metal–organic frameworks (MOFs) have traditionally been developed with a focus on applications such as gas storage, catalysis, and separations. More recently, MOFs have been investigated for the removal of toxic gases through both adsorptive and reactive mechanisms. This chapter begins with an overview of filtration and the important methods for evaluating MOFs for use in toxic chemical removal, including adsorption isotherms, breakthrough testing, nuclear magnetic resonance evaluation, and surface science techniques. Next, a discussion on modeling MOF topology and functionality as pertaining to toxic gas removal is provided as a complementary technique to experimental methods. Finally, several case studies of archetypal MOFs such as HKUST-1, UiO-66 analogs, and others are discussed in detail for removal of toxic gases such as ammonia, chlorine, nitrogen dioxide, and chemical warfare agents.