The use of hemispherical concave specimen is proposed to evaluate orientation-dependent etch rate of single crystal silicon. Etch rate is calculated from dimensional change of the hemisphere during etching. Etch rate distribution to the total orientation has been obtained for the etchant of 40wt%KOH aqua solution. The orientation showing maximum etch rate was [110] at 40°C. It deviates from [110] with an increase of temperature. The maximum point seems to move toward [320]. This fact indicates that the etched profile varies with etching temperature even when the etchant and the initial masking pattern are the same. The effect of temperature on the etch profile is experimentally proved. Variation in etch profile according to the change in temperature is theoretically explained by the etch rate data.