Triarylmethyl radicals, TAMs, are used as persistent paramagnetic probes for EPR spectroscopic and imaging applications and as hyperpolarizing and contrast agents for MRI and proton-electron double-resonance imaging, PEDRI. Recently we proposed the concept of dual function pH and oxygen TAM probes based on the incorporation of ionizable groups into the TAM structure (J. Am. Chem. Soc. 2007, 129, 7240–7241). In this paper we report the synthesis of deuterated derivative of phosphonated trityl radical, pTAM. The presence of phosphono substitutes in the structure of TAM provides pH sensitivity of its EPR spectrum in the physiological range of pH from 6 to 8, the phosphorus hyperfine splitting being convenient and highly sensitive pH marker (spectral sensitivity, 3ΔaP/ΔpH≈0.5 G/pH unit; accuracy of pH measurements, ±0.05). In addition, substitution of 36 methyl protons with deuterons significantly decreased the individual linewidth of pTAM down to 40 mG and, as consequence, provided high sensitivity of the linewidth broadening to pO2 (ΔH/ΔpO2≈0.4 mG/mmHg; accuracy of pO2 measurements, ≈1 mmHg). The independent character of pH and [O2] effects on the EPR spectra of pTAM provides dual functionality to this probe allowing for an extraction of both parameters from a single EPR spectrum.