To investigate the characteristics of spray etching, which has been used for producing precision metal goods, spray etching tests of 42 Alloy using ferric chloride solution were carried out. By varying fundamental operating factors (ferric chloride concentration, etchant temperature and spraying pressure), we studied their effects on etch rate and etch factor which is an index of accuracy. The etch rate showed a convex curve against ferric chloride concentration. The higher the concentration, the smoother the sample surface. Spraying pressure had a significant effect on etch factor. Higher spraying pressures improved etch factor. The activation energy is 29 kJ/mol when the photo-resist hole diameter is 250 mu m.