The effect of composition on initial permeability (μi) and relative loss factor (tan δ/μi) as the function of frequency and temperature is studied for Ni1-xZnxFe2O4 (x = 0.2, 0.3, 0.4 and 0.5) prepared by flash combustion technique. The ferrite powder prepared by this technique was calcined at 900 °C. The uni-axially pressed samples were sintered at temperatures of 1150, 1250 and 1350 °C. The experimental results indicate that the initial permeability of Ni-Zn ferrites increases with increasing zinc content when measured as the function of frequency at constant room temperature. The dependence of initial permeability with respect to temperature shows the decrease in the Curie point with increase in zinc content, is the normal behaviour of ferrites. The low value of relative loss factor of the order of 10-2 to 10-4 in the frequency range from 10 kHz to 13 MHz indicates that the ferrites are relatively high purity. The microstructural features were also studied and reported. The Zn ion concentration greatly influences the initial permeability as well as relative loss factor.