The structural and magnetic properties of melt-spun ribbons with nominal composition of Mn55Bi45 were investigated using X-ray diffraction, transmission electron microscopy and magnetometer measurements. A large coercivity (Hc) of 0.8T was observed in the as-spun ribbons. Microstructure reveals the presence of Mn–Bi nanoparticles in the as-spun ribbons. Coercivity was found to increase with increasing temperature with a maximum coercivity of 1.4T at T=503K in the as-spun ribbons. Heat treatment of the as-spun ribbons resulted in the increase of LTP MnBi phase. Spin reorientation transition (TSR) was observed around 100K.