Molecular copper complexes that model structural and/or functional aspects of the two copper enzymes in bacterial denitrification are reviewed, with a focus on models of the catalytic active sites. Copper nitrite reductase (CuNiR) features a mononuclear type-2 catalytic site, and synthetic model complexes have provided key insights into structural aspects of the binding of nitrite (NO2−) to copper, as well as into the feasibility (or lack thereof) of potential nitrosyl (NO) adducts of copper along the catalytic pathway. A rich array of mechanistic information is available for model complexes that exhibit nitrite reductase activity, although very few model systems proceed through the biologically relevant nitrite binding mode. Nitrous oxide reductase (N2OR) features a tetranuclear catalytic site, with the 4Cu : 1S form (CuZ*) being the most relevant system for model studies. The synthetic difficulty in controlling Cu : S stoichiometry during cluster assembly has presented a challenge to the modelling community, and recent efforts to overcome this challenge are presented. Molecular copper complexes capable of activating gaseous N2O do not feature copper–sulphide cores, but nonetheless have provided crucial data regarding the roles of polarised metal–metal interactions, labile coordination sites and potential N2O binding modes in the activation and reduction of N2O by copper.