A study was made relating C-14, delta C-13, and deltaD isotopic abundances for 11 different flavor materials: acetaldehyde, amyl acetate, anethole, benzaldehyde, cinnamic aldehyde, ethyl acetate, ethyl butyrate, ethyl caproate, linalool, methyl salicylate, and vanillin. Deuterium/hydrogen (deltaD) isotopic ratios, determined in these flavor materials, were found to be sufficiently uniform and different for those of natural sources and fossil fuel derived sources. deltaD values for the natural or modem derived flavor materials were consistently more depleted in deuterium content than the synthetic material. The mean deltaD value for the natural and synthetic compounds, respectively, were found to be the following: acetaldehyde, -202 and -76 parts per thousand; amyl acetate, -292 and -123 parts per thousand; anethole, -85 and -58 parts per thousand; benzaldehyde, -111 and -58 parts per thousand (synthetic I) or +600 parts per thousand (synthetic II); cinnamic aldehyde, -120 and -27 parts per thousand (synthetic I) or +515 parts per thousand (synthetic II); ethyl acetate, -242 and -98 parts per thousand; ethyl butyrate, -238 and -57 parts per thousand; ethyl caproate, -246 and -220 parts per thousand; linalool, -297 and -196 parts per thousand; methyl salicylate, -130 and -71 parts per thousand; and vanillin, -77 and -20 parts per thousand. Correlation between C-14 activities representing the degree of naturalness covaried with deltaD values, especially with ester compounds. The implications is the deuterium content could be used in determining adulteration by addition of synthetic components or at least suggest further testing for those flavor materials which fall outside the normal range of isotopic values.