A process for the preparation of a copper containing zeolitic material having CHA framework structure and a composition comprising the molar ratio (n YO2):X2O3 wherein X is a trivalent element, preferably Al, Y is a tetravalent element, preferably Si, and wherein n is preferably at least 20, and wherein the calcined material comprises crystallites having edges, and at least 90% of the crystallites have edges with a mean length in the range of from 1 to 5 micrometer. The process comprising the preparation of an phosphor-free aqueous solution containing at least one source for X2O3 and at least one source for YO2, at least one structure directing agent suitable for the preparation of a zeolitic material having CHA framework structure, and at least one Cu source, and the process further comprising the hydrothermal crystallization of said aqueous solution obtaining a suspension containing the copper containing zeolitic material having CHA framework structure.