The ISO-SWS spectrum of planetary nebula NGC 7027

We present the infrared spectrum of the planetary nebula NGC7027 observed w ith the Short Wavelength Spectrometer (SWS), on board the Infrared Space Ob servatory (ISO). These data allow us to derive the electron density and, to gether with the IUE and optical spectra, the electron temperature for sever al ions. The nebular composition has: been determined, the evolutionary sta tus of the central star is discussed and the element depletion in the nebul a is given. We conclude that tile progenitor was: a C-rich star with a mass : between 3 and 4 M-circle dot.