Er3+/Yb3+ co-doped potassium-lead-germanate (70GeO2-20PbO-10K2O) glasses with a fixed concentration of Er3+ ions (0.5 mol. %) and different concentrations of Yb3+ ions (0, 0.5, 1.5, and 2.5 mol. %), have been synthesized by the conventional melting and quenching method. The structure and vibrational modes of the glass network were investigated by the infrared absorption and Raman spectroscopy. The thermal behavior of all glass samples was investigated by the differential thermal analysis. Infrared-to-visible frequency upconversion process was investigated in all glasses. Intense green and red upconversion emission bands centered at around 532, 546, and 655 nm were observed, underallglasses.Intense excitation at 980 nm of diode laser at room temperature. The dependence of these emissions on the excitation power was investigated.