A method for hyperpolarizing spins includes the following steps: a) placing a sample containing spins (s) in a stationary magnetic field; b) magnetically coupling the sample to an electromagnetic resonator having a resonance frequency ω0 equal to the Larmor frequency of the spins in the stationary magnetic field, such that the coupling with the resonator dominates the relaxation dynamics of the spins; and c) reducing the effective temperature of the electromagnetic field inside the electromagnetic resonator below its physical temperature and that of the sample; whereby the polarization of the spins of the sample is established at a value higher than its thermal equilibrium value. An apparatus for implementing such a method is also provided.