The influence of sodium silicate amount on the setting time and EXO temperature of a complex binder (CB) consisting of high-aluminate cement (HAC), liquid glass and metallurgical slag (MS) has been investigated. Two maximums were observed on exothermal curves during the hydration process of CB, in which sodium silicate quantity was >4%. The first maximum of exothermic temperature occurred due to the reaction proceeding between sodium silicate and the slag. The second maximum of the exothermal effect was observed after the final set in the already hardened CB, and it was accompanied by the hydration of HAC, the degree of which depended on the sodium silicate amount in CB.