Temporary restoration material is used before permanent restoration can be placed. The use of temporary restoration in the oral cavity can be exposed by acid from saliva. Salivary pH ranges from 7.4 and varies in accordance with the concentration of hydrogen (acid) ions in the oral cavity. Dental materials are more stable in the oral cavity with normal range pH and tend to dissolve in acidic pH. The purpose of this study was to discover the effect of salivary pH on the solubility of calcium sulphate based temporary restoration. The method of the study was an experimental laboratory with 28 samples with 7mm diameter and 2mm height then divided into 4 groups, those were: pH 4, pH 6.8, pH 8, and control group. The solubility of the sample was measured by mass alteration. Data of the experiment were analyzed by One Way ANOVA and Post Hoc examination with Least Significant Different. The average of solubility in the group of pH 4 sample has a significant difference with the other 3 groups (p<0.05). The conclusion of this study is that there is an effect of salivary pH on the solubility of calcium sulphate based temporary restoration.