Abundances of Planetary Nebulae BD+30 3639 and NGC 6543

Infrared spectra taken with the Short Wavelength Spectrometer on board ISO and UV observations with IUE of planetary nebulae BD+30 3639 and NGC 6543 are presented. The extinction derived using infrared lines for BD+30 3639 is , slightly higher than previous determinations. For NGC 6543 the extinction found from the hydrogen lines is . Infrared, optical and ultraviolet data have been used to derive the physical parameters of the nebula. BD+30 3639 has an average K and . In the case of NGC 6543 a K and have been found, in agreement with previous determinations. The element abundances have been derived and compared to those found in the Sun and O, B stars. This comparison gives a hint of the mass of the progenitor stars from which they evolved.