Abstract
In order to study the element abundance distribution in the Galaxy, infrared spectra between 2.3 and 196 mu m were taken towards a sample of ultracompact H II regions using the two spectrometers (SWS and LWS) on board ISO. The sample spans a large range in galactocentric distance (0 to 20 kpc). The fine structure lines of O, N, Ne, Ar, S, C and Si are detected in most of the sources with some species (O, N, S, Ne, and Ar) present in different stages of ionization. From the measured line fluxes, the properties of the ionized gas can be precisely constrained.
