A Pechini-based chemical synthesis route was used to produce powders of Na0.5K0.5NbO3 (NKN). The thermochemistry of the gel was investigated using thermogravimetric analysis-fourier transform infrared (TGA-FTIR) evolved gas analysis; in addition, powder FTIR was used to analyze the gel residues after different heat treatments. The final decomposition of the organic components occurred at similar to 650 degrees C. However, hydrated-carbonated secondary phase(s) were detected by FTIR in powders that had been heated at 700 degrees C, indicating that the NKN nanopowders are susceptible to a reaction with atmospheric moisture and carbon dioxide. The NKN particle sizes were in the range 50-150 nm after decomposition at 700 degrees C.