In this work, the influence of surrounding ambient atmosphere on the stability of electroluminescent (EL) porous Si (PS) diodes is examined. We have fabricated electroluminescent porous Si layers from anodic oxidation of (1) epitaxially grownp‐type layers onn‐type Si substrates; (2)n‐type substrates with Au/Pd contacts; (3)p‐type substrates with Au/Pd contacts. These structures are characterized using photoluminescence (PL), EL, and infrared (IR) spectroscopies, as well as scanning electron microscopy (SEM). In the case of the porous Si structures fabricated fromp‐njunctions, such structures yield orange emission with maxima near 620 nm upon the application of moderate applied voltages (3–7 V). For each type of diode, it is found that in strong oxidizing environments, EL intensity degrades completely within 30 min; in contrast, the integrated intensity remains essentially unchanged in the same time frame in the presence of a vigorous flow of inert gases such as nitrogen and argon. Infrared spectroscopic studies strongly suggest that electroluminescence degradation is related to porous silicon surface oxidation. ©1995 American Institute of Physics.