A catalyst for the selective catalytic reduction of NOx comprises a zeolitic material which comprises (A) one or more zeolites having a GME framework structure containing YO2 and X2O3, and optionally further comprises one or more zeolites having a CHA framework structure containing YO2 and X2O3, and/or comprises, (B) one or more zeolite intergrowth phases of one or more zeolites having a GME framework structure containing YO2 and X2O3 and one or more zeolites having a CHA framework structure containing YO2 and X2O3, wherein Y is a tetravalent element, and X is a trivalent element, and the zeolitic material contains Cu and/or Fe as non-framework elements in an amount ranging from 0.1 to 15 wt. % calculated as the element and based on 100 wt. % of YO contained in the zeolitic material. Also provided are a process for its preparation, and a use in a method for the selective catalytic reduction of NOx.