Nonenzymatic oligomerization reactions represent a model for studying the prebiotic replication of informational macromolecules. To explore the fitness of acyclic oligonucleotides in these reactions, we have synthesized a series of DNA hairpins appended with templates incorporating atactic glyceryl cytosine residues. Atactic glyceryl cytosine units are found to impede, but not to block, template-directed oligomerization of guanosine 5'-phosphoro-2-methylimidazole (2-MeImpG). Evidence suggests that both D and L glyceryl nucleoside configurations at a given template position contribute to product formation. The stability of DNA duplexes bearing isolated glyceryl cytosine residues has also been investigated. Duplex thermal denaturation experiments indicate that an atactic glyC. dG base-pair is intermediate in stability between a dC. dG pair and a dT. dG mismatch.