High-intensity laser photoionization of cytosine and its derivatives has been used to generate the parent radical cations and to study the pathways by which they react. The parent radical cations are generally unstable at 77 K and undergo deprotonation to neutral radicals. The radicals formed on photoionization of cytosine, 3-methylcytosine, and 5-methylcytosine all give EPR spectra consistent with N1 alpha-deprotonation, In contrast, photoionization of 1-methylcytosine, 5’-dCMP, 5’-CMP, and poly C in neutral glasses gives rise in each case to EPR spectra at 77 K that are consistent with loss of a proton from the N1 carbon, which in the case of the nucleosides and nucleotides generated the C1’ radical. In alkaline glasses photoionization of 5’-dCMP gives a sextet spectrum that has been tentatively assigned to the C3’ radical. Finally photoionization of N1-substituted 5-methylcytosine derivatives in neutral glasses gives spectra consistent with loss of a proton from the base methyl group as observed previously with thymine nucleosides. The direct formation of sugar radicals from the radical cations of cytosine derivatives at 77 K is an important observation and contrasts with the properties of the radical cations derived from the other DNA nucleosides, and its relevance to radiation damage to DNA is discussed.