<p>This study investigates the propagation of Rayleigh waves in an orthotropic layer lying over an orthotropic half-space with nonlocal effects and diffusion. The analysis addresses the impact of nonlocality and diffusion on the wave characteristics within an orthotropic medium, which exhibits complex anisotropic properties. By employing the dual-phase-lag (DPL) model, we explore how these factors influence wave behavior, including phase velocity, attenuation coefficient, specific loss and penetration depth. The nonlocal effects are incorporated to account for spatial variations that extend beyond local interactions, while diffusion processes are considered to capture heat conduction and mass transfer phenomena. The results reveal that nonlocal and diffusion effects significantly alter the propagation characteristics of Rayleigh waves, demonstrating variations in phase velocity, attenuation coefficient, specific loss and penetration depth compared to traditional models. This research provides insights into the fundamental mechanisms influencing wave propagation in advanced material layers and has potential applications in material design and structural health monitoring. The findings contribute to a deeper understanding of wave dynamics in complex media and highlight the importance of considering nonlocal and diffusion effects in practical scenarios.</p>