Substituted W-type hexaferrite nanoparticles of SrZn2-xCox/2Nix/2Fe16O27 were synthesized by a chemical co-precipitation method. The X-ray diffraction results confirmed that W-type ferrite was identified as the main phase in whole samples in the range of x = 0-0.4. According to magnetic hysteresis loops, with increasing of substituted cations, saturation of magnetization increased and coercivity decreased due to crystalline site occupation of Zn with Ni and Co cations. The microwave reflection loss analysis results in the K-u band (12-18 GHz) show that the highest value of reflection loss of samples was -29.11 dB at frequency of 14.57 GHz with an absorption bandwidth of more than 6 GHz by choosing reflection loss value of 10 dB as a reference. The results indicate that, the sample with appropriate amount of substituted cations hold great promise for microwave device applications. (C) 2015 Elsevier Ltd. All rights reserved.