The present invention relates to a method and apparatus for detection of hydrogen sulfide in downhole operations. A downhole tool is provided with a coupon adapted to react at varying degrees to exposure to concentrations of hydrogen sulfide. The downhole tool is positioned in the wellbore with the coupon(s) exposed to downhole fluids. A reaction to a change in the coupon, such as coloration, is used to determine the presence and concentration of hydrogen sulfide.