We report the zero kinetic energy photoelectron spectrum of the propargyl radical, C3H3. From the spectrum an ionization energy of 69 953 +/- 10 cm(-1) (8.673 eV) is deduced. Vibrational frequencies are obtained for the totally symmetric normal modes of the propargyl cation, as well as some combination and overtone bands. Both the frequencies and the relative intensities agree well with the predictions from recent ab initio calculations. (C) 2000 American Institute of Physics. [S0021-9606(00)02006-7].