The objective of this study is to investigate if trityl biradicals could lead to more efficient dynamic nuclear polarization (DNP) for low gamma nuclear spins at low temperature (≈1 K) than a trityl monoradical. Three novel trityl biradicals of different size are synthesized, characterized and employed for hyperpolarization of [1-¹³C]pyruvic acid at 3.35 T and 4.64 T. Intramolecular electron–electron distances are obtained via dipolar couplings from electron paramagnetic resonance (EPR) spectroscopy at X-band and W-band that match well with calculated molecular structures. Steady-state DNP levels and build-up times are measured as function of radical concentration, magnetic field strength and microwave frequency for each biradical. Similar maximal DNP is obtained with all studied biradicals whereas a twice as high polarization is achievable with the monoradical. Both the biradicals and the monoradical show approximately a doubling of the polarization when increasing the field strength from 3.35 T to 4.64 T. Biradical concentrations at maximum polarization are several times lower than the optimum monoradical concentration, but the penalty is a much longer build-up time. Adding a small amount of Gd³⁺ to the samples (molar fraction of typically 100 ppm) has the same effect on DNP with the biradicals as with the monoradical. The electron longitudinal relaxation time T_1e is found to be independent of the radical type and the field strength in this study. The same dependence of T_1e on the trityl concentration is observed for all radicals. A considerable shortening of the ¹³C longitudinal relaxation time is observed for biradicals which agrees with the shortened build-up time compared to the monoradical at the same trityl concentration. This is probably the reason for lower DNP levels with trityl biradicals.