The P300 (P3) event-related brain potential (ERP) was elicited with auditory stimuli in order to compare three different tasks and to assess the effect of ageing from childhood to adolescence. Seventy-two subjects, ranging in age from 6 to 14 divided into three age groups, were selected for this study. In the active task, the subject was required to discriminate between standard and target tones (oddball); in the passive task condition, the subject did not respond to either the standard or target stimulus; in the single task, a target but not a standard tone stimulus was presented and the subject was required to react to the target tone. Our results show that the passive sequence and the single-tone paradigm yielded similar P300 waveform to those obtained from the active task. Separate age/ERP component latency and amplitude linear regression were computed. A significant negative correlation between age and P3 latency was found. The event-related potential P3 wave shows consistent and significant age-related changes in human cerebral function, regardless of the methodology used. These findings suggest that the passive and single-tone paradigms can be a useful way to elicit the P3 ERP component.