The quantification of hydrogen sulphide (H2S) by Selected Ion Flow Tube coupled with Mass Spectrometry (SIFT/MS) was investigated for application in industrial emission context, usually faced with concentrations of water vapour higher than the saturation at room condition. H2S concentrations measured by SIFT/MS (using nitrogen as carrier gas and flow tube temperature at 119°C) were affected by water content, reducing the sensibility for H2S measurements. Accurate concentrations were obtained when the influence of water was considered on SIFT/MS analysis, requiring although the information about water content in the sample. In addition, the association of low concentration of H2S (around 50 ppbv) and high humidity level (4.0 %vol of water) was highlighted as a critical point for measuring H2S by SIFT/MS, due to the sensibility reduction as function of water content and the measurement uncertainty enhancement at low signal intensity.