The present invention relates to a material with orthophosphate and having a high solubility which can be used as a bioactive bone replacement material and as a substrate material in biotechnology. According to .sup.31P-NMR measurements, the new material comprises Q.sub.0-groups of orthophosphate and Q.sub.1-groups of diphosphate, the orthophosphates or Q.sub.0-groups making up 65 to 99.9% by weight relative to the total phosphorus content of the finished material and the diphosphates or Q.sub.1-groups making up 0.1 to 35% by weight relative to the total phosphorus content of the finished material, and wherein according to X-ray diffractometric measurements and relative to the total weight of the finished material, 35 to 99.9% by weight of a main crystal phase consisting of Ca.sub.10Na(PO.sub.4).sub.7, Ca.sub.10K(PO.sub.4).sub.7, mixtures thereof or mixed crystals according to the general formula Ca.sub.10K.sub.xNa.sub.1-x(PO.sub.4).sub.7, where x=0 to 1, is contained in the bone replacement material and 0.1 to 25% by weight of a substance selected from the group consisting of Na.sub.2CaP.sub.2O.sub.7, K.sub.2CaP.sub.2O.sub.7, Ca.sub.2P.sub.2O.sub.7 and mixtures thereof is contained as a secondary crystal phase, and the X-ray amorphous phases contained besides the main crystal phase jointly make up 0.1 to 65% by weight.