A semiconductive charge- transfer solid was prepared by the reaction of cytosine and TCNQ. Cytosine molecules formed a hemiprotonated cytosine pair by complementary triple hydrogen bonds, and the pairs were then linked by complementary double hydrogen bonds to form infinite ribbons. TCNQ molecules formed uniform segregated columns. The robust hydrogen bonds linking the cytosine and TCNQ molecules preserved the uniform arrangement even at low temperatures. Such structural regulation demonstrated a high conductivity of 3 x 10(-2) S cm(-1) in a fully ionic TCNQ salt by virtue of large transfer interaction and short interplanar distance of TCNQ molecules.