The surface phase diagram of S/Ni(111) in the temperature range from room temperature to 900 K has been established by reflection high-energy electron diffraction observations in consultation with previously reported data. The temperature dependence of surface diffusion coefficient of sulfur in a p(1 x 1) phase was measured with micro probe Auger electron microscopy from 513 to 597 K. The diffusion coefficient in the p(1 x 1) phase in the coverage region from 0.05 to 0.10 ML is expressed as: D (cm(2) s(-1)) = 2 x 10(3) exp[-1.1+/-0.1(eV)/k(B)T]. (C) 2000 Elsevier Science B.V. All rights reserved.