Observations of 10 microwave transitions of the molecules SiO, HCN, HNC, SiS, HC_3_N, CS, SO, and ^13^CO are presented in a total sample of 47 evolved stars. The studied sources are mainly O- and C-rich standard AGB stars, as well as O-rich red supergiants, S-type stars, protoplanetary nebulae and detached envelopes. We also take into account observations of these transitions, as well as of ^12^CO J=1-0, from the literature. The observations were carried out during May and September 1991 and June 1992 with the IRAM 30-m radiotelescope at Pico de Veleta (Spain); the resolution is 1MHz for 3mm data (100GHz) and 2 MHz for 2 and 1mm data (150 to 300GHz).