Abstract A Co-P alloy having a mixed amorphous/crystalline structure was produced by electrochemical deposition. X-ray spectra, differential scanning calorimetry and scanning electron microscopy were performed in order to obtain the structural characterization. A comparison of the new kind of material with known amorphous and crystalline alloys was also made on the basis of initial magnetization curves, electrical resistivity and standing magnetoelastic wave amplitudes. Differential scanning calorimetry reveals that the amorphous component in the mixed structure sample does not include one of the two disordered phases that are present in the completely amorphous material. The measured physical properties are explained by means of the structural characteristics and the related phosphorous content. In the new type of material a very low magnetostriction value is predicted and its effect on the magnetoelastic wave amplitude is demonstrated.