Microstructure and magnetic properties of high Bs Fe 85Si2B8P4Cu1 nano-crystalline alloy were tailored. The Bs ∼1.85T and low coercivity Hc ∼6A/m were obtained by conventional annealing (i.e., one step) at a heating rate of ∼400°C/min. While one step annealing process produces a fairly stable nanostructure, for short times at temperatures <425°C, the nanostructure and concomitant magnetic properties of this alloy are shown to be tunable by two step annealing process. Nanocrystalline ribbons with grain size (D) ranging from ∼15 to 32nm, H c ∼6 to 140A/m and core-loss at 1.5T, 50Hz ∼0.39 ∼5.0W/kg were obtained. The Hc of Fe85Si2B 8P4Cu1 alloy is shown to vary as D6, but a small deviation was noticed, which may be due to weak anisotropy.