This research studies the catheter friction thermal energy generation and saline temperature in rotational atherectomy (RA). RA is a catheter-based procedure utilizing a high-speed (typically 130,000 to 210,000 rpm) miniature grinding wheel to remove hardened calcified plaque inside the artery to restore the blood flow. During RA, elevated temperature due to the friction within the catheter may lead to complications such as slow-flow/no-reflow and myocardial infarction. RA experiments were conducted to measure the catheter temperature. An advection-diffusion model with inverse heat transfer solution was developed to estimate the spatial and temporal distributions of saline temperature and study effects of the rotational speed, catheter insertion length, and flow rates of blood-mimicking water and saline. The saline temperature rise is higher with higher wheel rotational speed, shorter insertion length, and lower flow rates of blood-mimicking water and saline. The wheel rotational speed and blood flow rate are the two most significant parameters affecting the saline and blood-mimicking water mixture temperature, which exhibits the highest (9 °C) rise under the 175,000 rpm wheel rotational speed and no blood-mimicking water flow (totally occluded artery) condition. This research provides insights and guidelines on RA device and clinical procedure from the thermal perspective.