It was found that the IR absorption bands appearing at 600 to 1600 cm−1, which had been previously assigned to the fundamental vibrations of [BiO3] or [BiO6] polyhedra, are due to residual carbonate ions (CO2−3) dissolved in Bi‐Sr‐Ca‐Cu‐O glasses. The concentrations of the remaining CO2−3in the Bi2.2Sr2Ca1Cu2Oxglasses that melted at 1100° and 1400°C are 170 × 10−5mol/cm3(3.3 mol%) and 3.2 × 10−5mol/cm3(0.25 mol%), respectively. The apparent activation energy for the dissociation of the carbonates was approximately 220 kJ/mol. The CO2−3content in the precursor glasses did not significantly affect the superconducting properties of the r