St. Petersburg State University, 7-9, Universitetskaya nab., St. Petersburg, 199034, Russian Federation Several varieties of the synthesis of fine spinel Mn 0. 7Zn 0. 3 Fe 2 O 4 samples: at different temperatures, in different media and with attempts to modify the surface in liquid phase, were carried out by a chemical co-precipitation. The study of the samples by X-ray analysis, FTIR spectroscopy, scanning electron microscopy (SEM) and microprobe elemental analysis, as well as the determination of the specific surface of the samples (BET) showed that all the samples have a spinel structure and composition Mn 0. 7 Zn 0. 3 Fe 2 O 4 and large enough (for a given type of sorbent) specific surface area (from 128 to 250 m 2 /g). All the samples had magnetic properties. Analysis of the sorption properties of these samples on the adsorption of the dye Congo red (CR), the concentration of which was determined using a spectrophotometer, SF 2000, showed that the samples which have been synthesized at 85°C; in a solution of 40% ethyl alcohol; or modified with polyvinyl alcohol have better adsorption properties.