Response features of mitral cells in the olfactory bulb were examined using principal component analysis to determine whether they contain information about odorant stimuli. Using microwire electrode array to record from the olfactory bulb in freely breathing anesthetized rats, we recorded responses of different mitral cells to saturated vapor of anisole (1 M), carvone (1 M), isobutanol (1 M), citral (1 M) and isoamyl actate (1 M). The responses of single mitral cells to the same odorant varied over time. The response profiles showed similarity during certain amount of period, which indicated that the response was not only depended on odor itself but also associated with context. Furthermore, the responses of single mitral cell to different odorants were observed with difference in firing rate. In order to recognize different odorant stimuli, we apply four cells as a sensing group for classification using principal component analysis. Features of each cell’s response describing both temporal and frequency characteristics were selected. The results showed that five different single molecular odorants can be distinguished from each other. These data suggest that action potentials of mitral cells may play a role in odor coding.