Abstract The reactive joining of an SiC f SiC composite with a zinc borate glass was studied at various temperatures, in order to optimize the joining process and to fully understand the reactivity between glass and composite. A temperature-dependent gas-producing redox reaction between ZnO and SiC was found to give gradual disappearance of the bubbles and crystallites always present in the range from to 1200 °C, and to yield a highly amorphous, bubblefree joint. This study permitted us to prepare single lap shear test specimens with minimal void content in the joint, i.e. a fully reacted and amorphous joint. The shear strength value obtained for these joints was higher than15 MPa at room temperature.