Silver chloride nanoparticles have been successfully prepared by an easy and quick method using solely the corresponding powder material and an ionic liquid. No other precursors or volatile solvents are needed, in contrast to other synthesis methods less environmentally friendly. The obtained nanoparticles were characterised by X-ray powder diffraction, UV-vis spectroscopy, transmission electron microscopy and scanning electron microscopy. The photocatalytic activity of the nanoparticles was tested for the degradation of industrial dyes under UV radiation. Orange II was chosen as a model dye to perform the experiments. The effect of dye concentration, catalyst loading and solution pH on this activity was studied. It was found that, in optimal conditions, a total degradation of the dye can be reached in only 30 min. The kinetic of the photodegradation followed a first-order reaction model, being proposed a possible photocatalytic reaction mechanism. The recyclability of the nanomaterial as catalyst was positively tested.