This invention relates to a cross-mixer for a developer system of a photocopier, particularly one with a two component development system, which mixes the developer mixture (1) to assure uniform lateral distribution of the toner, (2) to assure uniform concentration of the toner mixture and (3) to triboelectrically charge the developer mixture.Adjacently offset rows of V-shaped baffles successively divide and intermix the developer mixture. Angled lifting plates interposed between successive rows of baffles scoop and lift the mixture so as to triboelectrically charge the same.