Ultraviolet photodissociation time-of-flight (TOF) mass spectrometry (MS) is described as a method for determination of peptide ion primary structure. Monoisotopic selection and bond-specific activation, combined with the rapidity of TOF MS analysis, render this technique invaluable to the rapidly expanding field of proteomics. Photofragment ion spectra of model peptides acquired using both post-source decay (PSD) focusing and TOF-TOF experimental methods are exhibited. Advantages of 193-nm photodissociation for de novo sequencing of peptide ions are discussed.