Chordomas are a rare slow-growing cancer and their standard of care is surgery with Radiotherapy (RT). Chordoma is highly radioresistant and requires high dose of RT that lead to toxicity in the surrounding tissues. We investigated whether proton beam radiation therapy (PBRT) response can be further enhanced in combination with hyperthermia (HT) as a radiosensitizer. We also explored cell survival at the end of the Spread-out Bragg Peak (E-SOBP) compared to middle of the SOBP (M-SOBP) of PBRT with and without HT. Chordoma cell lines were treated with HT followed by PBRT at both E-SOBP and M-SOBP. Clonogenic assay was performed in triplicates for a dose response survival. HT with PBRT significantly killed (p<0.05) more cells at M-SOBP and E-SOBP compared to PBRT without HT. Our results provide in vitro evidence on effects of HT as a novel additive treatment to increase PBRT effectiveness in Chordoma cell lines.