Looks to be a generic 98 Mauser bayonet. They were made all over Europe, from 1898 to around the end of WW2. From the length I would date it from after WW1, (I would expect a WW1 blade to be longer) but putting a hard date to it would be impossible without knowing the country of origin, and the maker.
I think the word on the blade is probably "ARTILLERIA" Which would make it a Spanish bayonet. At "about" 20 inches it would be for the Spanish 1916 Short 7mm Mauser Rifle, but it would also fit the 1893 Spanish Mauser.
Edit : It probably would not have been used in WW2 as such, but it could have seen use during the Spanish Civil War.