SUMMARY Objective: The objective of this triple-blind, split-mouth, randomized clinical trial was to evaluate the bleaching efficacy and tooth sensitivity of an in-office bleaching agent submitted to different storage temperatures (room temperature at 21.04°C±3.13°C or refrigeration at 5°C). Methods and Materials: Thirty volunteers were selected who had central incisors with color A2 or higher. The volunteers' maxillary hemi-arches received either the bleaching treatment with room temperature or refrigerated storage temperatures (two sessions of 3×15 minutes, one-week interval). Color variation was evaluated by subjective (Vita Classic and Vita Bleachedguide) and objective methods (Vita Easyshade spectrophotometer). Tooth sensitivity was evaluated with the visual analog scale (0–10) and the numerical rating scale (five points). The consistency of bleaching gels was evaluated by flow test, and pH was measured, both in triplicate. Color variation (SGU) and ΔE were analyzed by paired t -test (α=0.05). The absolute risk of pain was assessed by McNemar test (α=0.05), data from the numerical rating scale by the Wilcoxon signed-rank test (α=0.05), and visual analog scale by paired t -test. Comparison between the times within each group was analyzed by Friedman test. Gel consistency and pH were analyzed by one-way analysis of variance and Tukey post-test. Results: Regarding the absolute risk of tooth sensitivity, no significant difference was observed between the groups. The relative risk for tooth sensitivity was 1.13 (95%, confidence interval 0.70–1.82). Both tooth sensitivity scales were statistically similar. The results of the subjective evaluation (Vita Classic: p =0.73, Vita Bleachedguide: p =1.00) and the objective evaluation ( p =1.00) of bleaching efficacy corresponded to the hypothesis of equality between groups after bleaching. Both pH values were around 7, and for the consistency test, there were significant differences between the groups ( p =0.002). Conclusions: Storage temperature of the analyzed in-office bleaching agent had no influence on tooth color effectiveness and tooth sensitivity.