Rapidly quenched microwires with a nominal composition of Fe 39Co 39Si 8B 14 (#A O), Fe 37Co 37Nb 4Si 8B 14 (#A N) and Fe 36Co 36Nb 4Cr 2Si 8B 14 (#A NC) have been investigated. Devitrification of as-quenched microwires showed that crystallization temperatures increased with simultaneous incorporation of Nb and Cr as in #A NC alloy. Addition of these elements also contributed to an increase in activation energy in #A N and #A NC alloys. Nb addition reduced the particle size, which became much finer in the case of the Cr-containing alloy. Although Nb addition did not have much effect on lowering the Curie temperature T C of the amorphous phase, Cr substitution lowered T C to 698 K from high values of 785 K and 787 K observed in the #A O and #A NC alloys, respectively. However, the Cr addition revealed a better Giant magneto-impedance (GMI) response compared to the other alloys. Such improved GMI properties in the Cr-containing alloy are attributed to lower values of the coercivity and magnetostriction in the alloy containing both Nb and Cr. © 2012 Elsevier B.V. All rights reserved.