We report here the successful synthesis of one-dimensional (ID) nanoribbons of nickel hydroxide crystallized in a new phase. This attempt is based on the treatment of freshly precipitated nickel hydroxide with high concentrations of nickel sulfate. The nanoribbons with monoclinic structure had a chemical composition of Ni(OH)(1.66)(SO4)(0.17)(H2O)(0.29), which was close to that of alpha-Ni(OH)(2). These nanoribbons were very pure single crystals, structurally uniform with typical widths of 5-25 nm, thicknesses of 1 -5 nm, and lengths of up to a few micrometers, and could be an ideal system for studying the physical and chemical properties of ID nanostructured electrode materials.