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The paper addresses the structural, crystallization, soft magnetic and Curie temperature behaviour of Co36Fe36Si4B20Nb4 alloy. The material, prepared in the form of ribbons by melt-spinning technique, was amorphous in the as-cast state. Differential scanning calorimetry (DSC) showed two stages of crystallization whereas thermal variation of electrical resistivity (TER) carried out to a higher range of temperature indicated three stages of crystallization. The first crystallization stage, which occurred at 845 K and 825 K in DSC and TER, respectively, was due to the formation of nanophase (CoFe)2Si as evidenced by X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The formation of these nanoparticles reduced the magnetocrystalline anisotropy, thereby revealing good soft magnetic properties in the samples annealed between 825 K and 875 K with coercivity less than 49.9 A m-1 (627 mOe) and susceptibility ∼ 0.72 × 103. In this optimum nanocrystalline state, the material also exhibited a high Curie temperature above 1100 K, opening the scope of the present nanocrystalline alloy for high temperature applications. [ABSTRACT FROM AUTHOR]