Imaging tumoral pH may aid in characterizing aggressiveness, metastasis, and therapeutic response. The study of hyperpolarized (HP) 13C chemical shift-based probes addresses some of the limitations of previously reported ratiometric methods, including HP 13C bicarbonate. We report the development of HP [2-13C,D10] diethylmalonic acid as a pH imaging agent, which exhibits a significant 13C chemical shift difference over the physiologic pH range. We demonstrate that this compound can be copolarized with tert-butanol to accurately measure pH in phantom studies. Furthermore, this HP compound showed high in vivo SNR in a murine model of prostate cancer.