The R3H domain has previously been identified as a conserved sequence motif in putative nucleic-acid-binding proteins from diverse range of organisms [1].. The 3D solution structure of the R3H domain from human Sμbp-2 has been determined by NMR spectroscopy[2]. In the present paper we report the results obtained from our binding studies of the R3H domain from human Sμbp-2 and mononucleotides. Our results show that the R3H domain binds mononucleotide mono-phosphates, and the dissociation constant of the complex is within the micro-molar region. It has a substantial preference for binding with deoxy-ribonucleotides over ribonucleotides, especially for the purine-containing bases. The R3H domain does not bind mononucleotide di-phosphates and triphosphates as well as unphosphorylated mononucleotides not present in the DNA and the RNA. The R3H domain has no affinity towards 3'-phosphorylated mononucleotides too. The binding site of deoxy-guanosine mono-phosphate is identified from perturbations of chemical shifts in the 2D [1H, 15N] HSQC spectrum. The obtained results suggest that the R3H domain is involved in DNA binding and could have a preference for binding with guanosine-rich DNA sequences.