A work or sports protective helmet, with a structure having a substantially convex outer surface; a substantially concave inner surface adapted to receive a user's head in engagement is provided. The helmet also has two coupling and decoupling elements for engagement an accessory, such as a visor, a mask, a net or a similar accessory, each of which can be engaged on a lateral portion of the outer surface of structure. Each coupling and decoupling element can be removed from the helmet and has a body having a coupling mechanism which allows the engagement and the disengagement of the accessory to/from the helmet when the coupling and decoupling elements are engaged on the latter.