We report the Co-substituting on the synthesis and properties of garnet type dysprosium ferrite nanopartides by basic composition Dy3Fe5-xCoxO12 (x = 0-0.06) synthesized through glycine assisted combustion method. A possible formation mechanism of synthesized Dy3Fe5-xCoxO12 samples by controlling the synthesis process has been proposed. XRD, FT-IR, XPS and VSM studies were used to investigate the compositional and magnetostructural properties of the prepared nanoparticles. XRD results confirm that all the samples are single-phase cubic garnet structure with mean crystallite size of 97-105 nm obtained from Scherrer method and 95-102 nm from W-H method. FT-IR analysis shows the presence of three expected bands in the frequency limit of 450-600 cm(-1) attributed to metal-O stretching vibration in tetrahedral site of garnet structure. A typical survey spectrum from XPS results confirmed the presence of Dy, Fe, Co and O elements in the samples. This study also to characterize the different oxidation states of the samples by fitting the parameters of high resolution Dy 4d, Fe 2p, Co 2p and O Is XPS spectra. The XPS data of Dy 4d spectrum show that Dy3+ ion occupy in dodecahedral (D) site. The XPS analysis of Fe 2p and Co 2p data suggests that (Fe3+ and Fe2+), (Co3+ and Co2+) are distributed in tetrahedral and octahedral sites. Magnetic study reveals that these nanoparticles exhibit ferromagnetism. The saturation magnetization, coercivity, anisotropy constant and remanent magnetization changes appreciably with increase in Co content in dysprosium ferrite. (C) 2015 Elsevier B.V. All rights reserved.