The study evaluated the effect of annealing temperature of non-wood, herbaceous ground briquettes on their density, hardness and fracture incidence. The study showed an average density of hay briquettes at 20 °C was 1 256.99 kg·m−3, whereas at 60 °C density increased to 1 369.44 kg·m−3. The analysis showed statistically significant differences in the average densities of briquettes, depending on their temperature. Temperature of briquettes also had a statistically significant effect on their hardness. In case the temperature increases from 20 to 60 °C both longitudinal and transverse cracks were observed for all samples.