Previous electrophysiological evidence supports categorical perception of Chinese lexical tones at the preattentive stage (Xi and colleagues). In this study, we examined participants' attentive responses to tonal continua in an event-related potential experiment that recorded their N2b and P3b oddball responses. We found that for both the N2b and the P3b component, the responses elicited by the within-category deviants were similar in the left and the right recording sites. However, the across-category deviants elicited larger responses in the left recording sites than in the right sites, reflecting conscious phonological processing of lexical tones. These results provide electrophysiological correlates of categorical perception of Chinese lexical tones in later stages associated with controlled processes.