Nanocrystalline Mn0.5Zn0.5Fe2O4 ferrite in SiO2 matrix has been prepared by sol-gel method. X-ray diffraction (XRD) study indicates the presence of single-phase spinel ferrite in the sample. The size of the particles, estimated by a transmission electron microscope (TEM), was found to be less that 20 nm. The magnetization measurement of the sample shows no hysteresis loss. The Mossbauer spectra consist of a sextet due to ferromagnetic particles and a doublet due to superparamagnetic nano-sized ferrite.