Purpose: To investigate the buffering capacity of dentin powder to the acidity of single-step self-etch adhesives, by measuring the pH changes at different time intervals. Materials and Methods: Recently extracted human molar teeth were selected. The enamel was grinded away and dentin pieces were then dehydrated and milled to fine powder. Dentin powder samples were divided into two main groups according to the single-step self-etch adhesive system tested (A); (A1) Single Bond Universal, while (A2) Futurabond® DC. Dentin powder was mixed with diluted self-etch adhesives, and pH changes were measured by a pH meter at different time intervals after the start of mixing. Data were analyzed by Tukey’s Honestly Significant Difference (HSD) test and Dunnett’s test at a significance level of (P<0.05). Results: One- way ANOVA test revealed statistically significant higher initial mean pH value of the Single Bond Universal adhesive compared to the initial mean pH value of the Futurabond DC. Moreover after mixing with the dentin powder, dentin powder was able to buffer Single Bond Universal adhesive acidity only after 30 seconds of contact at pH=3.64 as revealed by One-way analysis of variance (ANOVA) test followed by Tukey´s Honestly Significant Difference (HSD) Test. While regarding Futurabond® DC dentin powder failed to buffer it at all the tested time intervals. Conclusion: Buffering action of dentin to self-etch adhesive systems was dependent on the initial acidity of adhesive system.