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[Display omitted] • 1. An anion substitution strategy is employed to improve conductivity and dielectric property. • 2. The type of anionic elements has a great influence on the EM wave absorption performance. • 3. NiCo 2 Se 4 and NiCo 2 Te 4 are reported for the first time in the field of EM wave absorption. With the extensive development of electrical communication equipment, the requirements for electromagnetic (EM) wave absorption materials have become more stringent to eliminate electromagnetic interference issues. Rational regulation of permittivity is an efficacious path to optimal EM wave absorption performance. NiCo based spinel materials (NiCo 2 X 4 , X = O, S, Se, Te) have been regarded as promising EM wave absorbing materials due to the advantage of controllable structure, inexpensive procedure and excellent dielectric property. Particularly, the element of anionic sites acts as a considerable role in determining the conductivity and permittivity of materials. Herein, spiny globose like NiCo 2 X 4 (X = O, S, Se, Te) are successfully prepared through hydrothermal and subsequent oxidation, sulfidation, selenization and tellurization methods, respectively. Due to the difference in electronegativity of the anion site elements, NiCo 2 Se 4 and NiCo 2 Te 4 show ameliorative conductivity and dielectric loss. An optimal reflection loss (RL) of −78.5 dB at 2.8 mm and an effective absorption bandwidth (EAB) of 5.28 GHz at 2.3 mm can be achieved for NiCo 2 Se 4. Moreover, due to enhanced dielectric performance, the matching thickness of NiCo 2 Te 4 is greatly improved, which the RL is −54.3 dB at 1.8 mm and EAB of 4.88 GHz at 1.6 mm. The synthesis of NiCo 2 Se 4 and NiCo 2 Te 4 , with remarkable absorption performance, is expected to provide an important reference for broadening the application of NiCo-based spinel in the field of EM wave absorption. [ABSTRACT FROM AUTHOR]