In this work, the influence of surrounding ambient atmosphere on the stability of electroluminescent (EL) porous Si (PS) diodes fabricated from anodic oxidation of epitaxially grown p-type layers on n-type Si substrates is investigated. These structures are characterized using photoluminescence (PL), electroluminescence (EL), and infrared (IR) spectrosopies, as well as scanning electron microscopy (SEM). Such structures yield orange emission with maxima near 620 nm upon the application of moderate applied voltages (3-7 V). In strong oxidizing environments, EL intensity degrades completely within 30 minutes; in contrast, the integrated intensity remains essentially unchanged in the same timeframe 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.