A process for mounting magnets in an electric motor rotor and an electric motor rotor, said rotor comprising: a lamination stack (10) provided with a plurality of axial channels (12) disposed around a central axial bore (11) and housing permanent magnets (20); and a rotor cage (30) formed by a pair of end rings (31), each seated against an adjacent end lamination of the lamination stack (10) and interconnected by a plurality of bars (32), said process comprising the steps of: forming an end, ring (31) with at least one inner radial projection (33) disposed radially external to the projection of the contour of an axial channel (12); mounting in each axial channel (12) at least one permanent magnet (20); and deforming each inner radial projection (33) in order to increase its radial extension the sufficient to radially cover at least part of the projection of the contour of said axial channel (12), defining a stop for axially retaining the respective permanent magnet (20). The present invention further provides an electric motor rotor having the characteristics defined above.