The performance characteristics of ridge waveguide In0.2Ga0.8As/GaAs multiquantum‐well lasers are reported. The lasers emit more than 50 mW/facet in the temperature range 20–100 °C in the fundamental transverse mode. The external differential quantum efficiency of 250‐&mgr;m‐long lasers is 0.4 mW/mA/facet. The internal optical loss is 14 cm−1. The optical gain is found to vary linearly with current. The increase in threshold current with increasing temperature in these lasers is primarily due to decreasing carrier lifetime (increased carrier loss) at high temperature. Increasing the heterobarrier height may further improve the high‐temperature performance of these devices.