Thin films of Praseodymium doped AlN are deposited on silicon (I 11) substrates at 77 K and 950 K by rf magnetron sputtering method. About 500-1000 nm thick films are grown at 100-200 watts RF power and 5-8 mTorr nitrogen, using a metal target of Al with Pr. X-rays diffraction results show that films deposited at 77 K are amorphous and those deposited at 950 K are crystalline. Cathodoluminescence studies are performed at room temperature and luminescence peaks are observed in a wide range from ultraviolet to infrared region. The most intense peak is obtained in green at 526 nm from amorphous films as a result from P-3(l) -> H-3(5) transition. In crystalline films the intense peak was obtain in red at 648 nm as a result from P-3(0) -> F-3(2) transition. Films are thermally activated at 1300 K for half an hour in a nitrogen atmosphere. Thermal activation enhances the intensity of luminescence. Two peaks at 488 nm and 505 nm merged after thermal activation. giving rise to a single peak at 495 nm.