<p>This study investigates the combined effects of porosity and strain rate on the mechanical behaviour of rocks under compressive and tensile loading conditions. Different levels of porosity ranging from 39 to 57% were tested across a wide range of strain rates, ranging from low (10⁻⁴–10⁰ s⁻¹) to high (≈ 700&#xa0;s⁻¹ in compression and ≈ 26&#xa0;s⁻¹ in tension) using a universal testing machine and split Hopkinson pressure bar, respectively. Results indicate that higher porosity significantly reduces rock strength in both compression and tension, regardless of strain rate. Also, strain rate sensitivity is evident for all porosity levels—strength increases with strain rate, which is quantified through dynamic increase factor (DIF). The influence of porosity on DIF, however, varies with loading mode. In compression, DIF values range from 2 to 2.5 for specimens with porosities of 57% and 39%, respectively. However, in tension, it remains relatively unaffected—DIF of 2.5 is obtained for all the porosities. Dynamic Young’s modulus also exhibits contrasting trends, such that it increases with strain rate in low porosity rocks but decreases in high porosity ones. Experimental data was normalized and compared with the Kimberley model, yielding a <i>β</i> value of 0.710, closely matching the theoretical 0.667 value, thus validating the model’s applicability. It establishes a strong correlation between flaw density and dynamic strength behaviour. These findings contribute to a better understanding of rate-dependent rock behaviour and support improved predictive modelling in dynamic environments such as drilling, blasting, and tunnelling.</p>