Gallium arsenide p-i-n radial junctions were fabricated by molecular beam epitaxy. The current-voltage characteristics of single nanowires were measured in the dark and under various illumination conditions including 1.5 AM. The total efficiency was 4.5%. Spatially resolved and power dependent photocurrent measurements indicate that the p-i-n junction is homogeneous along the nanowire. Electroluminescence measurements show an emission peak at about 1.4 eV, further corroborating the good quality of the nanowire. These results constitute an important progress for the use of nanowires in photovoltaic applications.