Results from radiochemical experiments with main emphasis on the gallium ones

In this work the radiochemical experimental technique and the up-to-date results from the radiochemical experiments that measured the interaction rate of solar neutrinos at Earth are reviewed and commented. Main emphasis is put on the gallium radiochemical experiments, as they are presently the only experimental way to probe at the sub-MeV scale both the oscillation scenario and the astrophysical solar models. These experiments are in a mature stage of their life and since many years are operated as neutrino observatories. Their impact on astrophysics and on neutrino physics will also be reported. They actually provide the best experimental constraint on the GNO vs. pp neutrino luminosity of the Sun.