Catalytic converter unit for an exhaust gas catalytic converter, in particular an SCR catalytic converter unit for an SCR catalytic converter of a marine diesel internal combustion engine, with multiple catalytic converter modules. Each catalytic converter module has a ceramic catalytic converter body through which exhaust gas flows and a metallic casing for the ceramic catalytic converter body. The respective ceramic catalytic converter body is received in the respective metallic casing and is surrounded in certain sections by the latter. The catalytic converter modules are positioned with first flowed-through ends on a support grating. A counter-brace is positioned at the opposite second flowed-through ends of the catalytic converter modules, and the catalytic converter modules are clamped between the support grating and the counter-brace.