The effect of preparation conditions on the properties of unsupported, high surface area Ni2P catalysts, prepared by adding citric acid (CA) to precursor metal salt solutions prior to drying, calcination and temperature-programmed reduction (TPR), is reported. The highest Ni2P surface area (similar to 220 m(2)/g) was obtained from a precursor solution with a P/Ni mole ratio of 2 and a CA/Ni mole ratio of 2 that was dried, calcined at 500 degrees C and reduced in H-2 at 650 degrees C. Adding CA to the precursor salt solution is shown to yield amorphous precursors after calcination, rather than crystalline NiO and Ni2P4O12 that was observed in the absence of CA, and the amorphous material yielded high surface area Ni2P when reduced at temperatures above 600 degrees C. The high surface area Ni2P favored the hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene (4,6-DMDBT) by the hydrogenation route, although some direct-desulfurization was observed on catalysts reduced at lower temperature in which significant metaphosphate species were identified. (C) 2010 Elsevier By. All rights reserved.