Data are presented on the electrical behavior and the reliability of postfabrication native‐oxide‐passivated visible‐spectrum AlGaAs–In(AlGa)P p‐n heterostructure light emitting diodes (LEDs). The LEDs are oxidized (H2O+N2, 500 °C, 1 h) after metallization, thus sealing all exposed AlGaAs crystal at cracks, fissures, and edges against atmospheric hydrolysis without degrading their light‐output characteristics. The current–voltage (I–V) characteristics of the oxide‐passivated LEDs are shown to exhibit normal p‐n diode behavior (∼1.9 V at 20 mA). The reliability of the oxidized devices in high‐humidity conditions is greatly improved compared to otherwise identical unoxidized LEDs. The latter degrade to less than 50% of initial output power at 1500 h accelerated life test in high‐humidity environments, compared to the oxidized LEDs not degrading noticeably in output power after 2500 h. © 1995 American Institute of Physics.