The present study investigated whether gender differences were present on the confidence judgments made by 8th grade Taiwanese students on the accuracy of their responses to acid-base test items. A total of 147 (76 male, 71 female) students provided item-specific confidence judgments during a test of their knowledge of acids and bases. Using the correctness of the answer responses, a confidence rating score, an unweighted rating score, and a relative confidence rating score were calculated for each respondent. The correlations between the boys and girls for each score area showed girls as scoring higher than boys in their knowledge of acids and bases, were more confident in this knowledge, and more willing to express different levels of confidence among the test items.