A monolithic thermal ink jet printhead (40) comprising a groove (45), a plurality of chambers (74) and nozzles (56) is manufactured by means of steps of: (203, 205) partially etching the groove (45) by means of a "dry" process and a "wet" process; (210) depositing a plurality of sacrificial layers (54); (212) obtaining a plurality of casts (156); (216) completing the etching of the groove (45) by means of an electrochemical process; and (220) removing the casts (156) and the sacrificial layers (54) in such a way as to obtain a plurality of nozzles (56) and chambers (74).