The hydrolysates of rice bran protein concentrate (RBPc) were prepared by two different methods of acid hydrolysis. First, RBPc was hydrolyzed by 0.5 N aqueous HCIat 95(+,ฐ)C for 12 and 36 hrs (mild hydrolysis) and freeze-dried. Second, RBPc was hydrolyzed by 4.0 N aqueous HCl at 95(+,ฐ)C for 72 hrs (strong hydrolysis) and spray-dried. Aroma components of RBPc hydrolysates were identified by using Gas ChromatographyOlfactometry (GC-0) and Gas ChromatographyMass Spectrometry (GC-MS). Aroma impact compounds were identified by Aroma Extract Dilution Analysis (AEDA) and Odor Activity Value (OAV). The predominant odorants in RBPc were 3-methylbutanal (malty), hexanal (grass), 2-aminoacetophenone (tortilla), E-2-nonenal (waxy), phenylacetaldehyde (rosy) and (+,b)-damascenone (apple sauce). The 2--aminoacetophenone (tortilla), which had 59 ng/g in RBPc, gave the same overall odor as that of RBPc. The FD chromatogram of RBPc hydrolysates, treated with 0.5 N HCl for 12 and 36 hrs, showed the similar patterns. Most of the predominant odorants tended to have the higher 1093FD factors in the hydrolysis time of 36 hrs than those in 12 hrs. Aroma impact compounds of RBPc hydrolysates, treated with 0.5 N HCl for 12 and 36 hrs, were 2-methoxyphenol (smoky), Furaneol(+,ฎ) (burnt sugar), sotolon (seasoning) and vanillin (vanilla), 3-methylbutanal (malty), E-2-nonenal (waxy), pvinylguaiacol (clove) and (3-damascenone (apple sauce). The overall "smoky" and "soy saucelike" aroma character of RBPc hydrolysate, treated with 4.0 N HCl for 72 hrs, was dominated by 2-methoxyphenol and 2,6-dimethoxyphenol. The 2-methoxyphenol and 2,6-dimethoxyphenol provided intense smoky notes. Particularly, 2-methoxyphenol gave the highest OAV values of 2,773, 17,650 and 6,265 in the RBPc hydrolysates with mild (12 and 36 hrs) and strong hydrolysis, respectively. The aromas with the highest 1093FD factors in RBPc hydrolysate (strong hydrolysis) were methional (cooked-potato), sotolon (seasoning), 2,6-dimethoxyphenol (smoky) and phenylacetic acid (sweet) with the values of 7, 5, 5 and 5, respectively. The results of Maillard model system (between the mixture of standard amino acids or single amino acid and fructose that treated with 0.5 N HCl for 36 hrs) indicated that leucine, isoleucine, methionine and phenylalanine were the precursors that generated 3-methyl butanal, 2-methyl butanal, methional and phenylacetaldehyde, respectively.