The invention relates to a method for determining a set of programming conditions for a given type of charge-trapping non-volatile memory device, comprising the steps of: (a) selecting different sets of programming parameters to be applied to the corresponding number of non-volatile memory devices of said type, (b) programming said number of non-volatile memory devices by means of the sets of programming parameters, (c) determining an actual spatial charge distribution of the charge trapping layer of each of the programmed devices, (d) determining the influence of at least one of the programming parameters on the spatial charge distribution, (e) determining an optimised value for at least one of the programming parameters, (f) entering each optimized value in said sets of programming parameters and repeating steps b) to e) at least once.