Supersulfated cement (SSC) was prepared from 85 wt. % granulated blast furnace slag (GbfS), 10 wt. gypsum (GY) and 5 wt. % Portland cement clinker (PCC). The main objective of this study is to improve the early strength of SSC with the addition of calcium format activator (CF). Different dosages of 0, 0.5, 1, 1.5, 2, 2.5, 3 and 3.5 wt. % CF were added to the SSC. The results showed that the water of consistency and setting times were increased as the content of CF increased. The total porosity and water absorption were slightly decreased with the increase of CF content, whereas the bulk density was improved an enhanced. The flexural and compressive strength also improved and gradually increased with CF addition. The combined water contents improved wand enhanced with the gradual replacement of CF. This was continued up till 3 wt. % CF, but with any further increase more than that, all of the hydration characteristics were diminished. The reacted or combined slag or sulfate increased with curing time. So, the CF would significantly improve, increase and also accelerate the early and later hydration characteristics of the SSC, and the dosage of 3 wt. % CF was the more pronounced effect compared with that of the control, i.e. the optimum CF dosage was 3 wt. %.