The present paper aims to study the effect of diffusion and rotation on a thermoelastic medium with voids in the context of the three-phase-lag model of thermoelasticity. The dimensionless governing equations are formulated, and then, the exact expressions for the displacement components, the temperature field, the concentration field, the stress components and the change in the volume fraction field are obtained using the normal mode technique. The results obtained from the thermal variations are validated by comparing the Green and Naghdi type III and three-phase-lag theories of thermoelasticity. The comparisons are shown graphically to explore the effects of diffusion, rotation and void parameters. Some particular cases of interest are also deduced from this investigation.