A process for producing &agr;-alumina containing &agr;-alumina single crystal particles characterized in that at least one of a transition alumina and transition alumina precursor is calcined in an atmosphere containing at least 1% by volume of hydrogen chloride at a temperature of not less than 600° C., preferably from 600 to 1,400° C., and more preferably from 800 to 1,200° C. Aluminum hydroxide, alum, aluminum sulfate, etc. are used as the alumina raw material capable of being converted to transition alumina on heating. &agr;-Alumina comprising octahedral or higher polyhedral &agr;-alumina single crystal particles have a high alumina purity above a given level, are fine and homogeneous, have a narrow particle size distribution, are not agglomerated particles, and can be obtained from raw materials of various kinds, purities, shapes, sizes, and compositions.