Several studies in the literature suggest that the frequency of weak oscillating magnetic fields (OMFs) significantly affects supercooling and freezing kinetics, although the effects described by different authors are apparently contradictory. To shed light on this matter, we froze pure water samples and 0.9% NaCl solutions in a 0.8-mT magnetic field at different frequencies (20, 50, 200, and 2000 Hz). Moreover, experiments with no OMF application were also performed to act as controls. Our results show that the application of a 0.8-mT OMF at frequencies between 20 Hz and 2000 Hz during freezing has no effect on the parameters that characterize either supercooling (time at which nucleation occurred and extent of supercooling achieved at the sample center) or freezing kinetics (precooling, phase transition, and tempering times), both in pure water and 0.9% NaCl solutions. More research is needed to elucidate all the factors that could affect OMF-assisted freezing. •The effect of the frequency of weak oscillating magnetic fields (OMFs) on freezing was evaluated.•Freezing curves of pure water and 0.9% NaCl solutions in a 0.8-mT OMF at 20–2000 Hz were compared to those obtained with no OMF application.•The application of a 0.8-mT OMF at 20–2000 Hz did not affect supercooling.•The application of a 0.8-mT OMF at 20–2000 Hz did not affect freezing kinetics.