Our research group is working on the Celtic coinage from northern Italy and has already carried out two measurement sessions at ISIS. A selection of 25 coins (drachmas) has been analyzed with the N.D. technique. Thanks to the results obtained, we can now trace a first silver debasement model in Celtic drachmas, between the IV and the II century B.C. Unfortunately the number of coins studied with neutron diffraction for each typology is still low: especially for typologies showing a higher complexity, would be necessary to increase the number of specimens. In the second measurement turn two rare silver coins of fractional coinage have been analyzed as well. This is one of the most mysterious topic in Celtic Italian numismatics. We would analyze a selection of these coins coming from the Museo di Antichità of Torino, which houses the richest hoard of fractional coins in the world.