High entropy alloys are a newly developed family of multicomponent alloys that consist of various major alloying elements, including copper, nickel, aluminum, cobalt, chromium, iron, and others. Each element in the alloy system is present at between 5 and 35 atom %. A high entropy alloy has numerous beneficial mechanical, magnetic, and electrochemical characteristics. This investigation discusses the corrosion resistance of the Al0.5CoCrCuFeNiBx alloys with various amounts of added boron. Surface morphological and chemical analyses verified that the addition of boron produced Cr, Fe, and Co borides. Therefore, the fraction of Cr outside borides precipitates was scant. The anodic polarization curves and electrochemical impedance spectra of the Al0.5CoCrCuFeNiBx alloys, obtained in 1 N H2SO4 aqueous solution, clearly reveal that the general corrosion resistance decreases as the concentration of boron increases. (c) 2007 The Electrochemical Society.