A Study of Chemical Abundances of Planetary Nebulae in M33

Eleven Planetary Nebulae (PNe) in the spiral galaxy M 33 have been studied with the CLOUDY 94.00 photoionization code (Ferland et al. 1998) using observations obtained with the 4.2 m WHT (La Palma, Spain) equipped with AF2/WYFFOS at a resolution of 3.0 angstrom/pixel in the spectral range 4300 to 7380 angstrom. A galactocentric gradient in O/H is suggested. The average [O/H] is very close to the same quantity from H II regions (Vilchez et al. 1988).