Using a single bath and controlling the deposition regime, it has been possible to grow electrochemically both CoNi films and nanowires of variable composition and crystalline structure. Low deposition potentials favour the formation of cobalt-rich hcp CoNi films, whereas fcc films (also cobalt-rich) can be obtained at more negative deposition potentials as a consequence of the faster deposition rate. By using membranes to grow CoNi nanowires, the control of the deposition rate is more difficult because the growth is strongly affected by the transport of the electroactive species into the channels: in this case, the structure of the nanowires is also affected by the type of the membrane used (nature, pore's diameter and length). Short nanowires (between 2 gm and 250 nm length) in membranes with decreasing pore diameter (200, 100 and 20 nm) have been electrodeposited in order to tend to monodomain magnetic nanowires. The magnetic properties of the different deposits related to size, shape, crystalline structure and composition were studied and interpreted. (C) 2013 Elsevier B.V. All rights reserved.