An embodiment solution for operating a non-volatile memory of a complementary type is proposed. The non-volatile memory includes a plurality of sectors of memory cells, each memory cell being adapted to take a programmed state or an erased state. Moreover, the memory cells are arranged in locations each formed by a direct memory cell and a complementary memory cell. Each sector of the non-volatile memory is in a non-written condition when the corresponding memory cells are in equal states and is in a written condition wherein each location thereof stores a first logic value or a second logic value when the memory cells of the location are in a first combination of different states or in a second combination of different states, respectively. In an embodiment, a corresponding method includes the following steps: selecting at least one of the sectors, determining an indication of the number of memory cells in the programmed state and an indication of the number of memory cells in the erased state of the selected sector, and identifying the condition of the selected sector according to a comparison between the indication of the number of memory cells in the programmed state and the indication of the number of memory cells in the erased state.