Aims:The main aim was to investigate the patterns and kinetics of substrate oxidation by Campylobacter jejuni and C. coli. Methods and Results: Substrate oxidation profiles by 100 strains were determined using oxygen electrode system. All the isolates tested oxidized formate, L L-lactate, cysteine, glutamine and serine with high oxidation rates and high affinity but varied in their ability to oxidize citric acid cycle intermediates, aspartic acid and serine. Conclusions: Based on the oxidation ability of a-ketoglutarate, succinate, fumarate and aspartic acid, Campylobacter strains tested were divided into three distinct metabolic categories. The first group was able to metabolize a-ketoglutarate, succinate, fumarate and aspartic acid; the second group was unable to oxidize a-ketoglutarate; and the third group was unable to oxidize, succinate, fumarate, and aspartic acid. Furthermore, serine oxidation rate enabled the differentiation of C. jejuni and C. coli. Significance and Impact of the Study: Overall, the results highlights the extensive metabolic diversity between and within Campylobacter species. In addition, the kinetic data of oxidized substrates obtained may improve the isolation procedures of the organism.