A reference standard for GHB free acid is not commercially available, making its analysis in forensic exhibits more difficult. GHB is typically found in liquid solution and in the presence of the lactone gamma-butyrolactone (GBL), which presents difficulty in Fourier transform infrared (FT-IR) analysis. The strong IR absorption of the GBL carbonyl band, the shifting of this band in liquid solutions, and the position of the oxygen-hydrogen bend for water can mask the main carbonyl band for GHB free acid. This study examined the prominent infrared (IR) spectral features of GHB (both free acid and carboxylate forms) and the lactone gamma-butyrolactone (GBL) and used a second derivative spectral data processing technique to resolve these spectral features from the water interference in the spectra of the neat liquid solutions. This was followed by the development of a procedure for the physical isolation of GHB free acid in order to generate reference material for the in-house IR spectral library. The use of second derivative FT-IR spectroscopy provided resolution of the free acid carbonyl band, and a presumptive test for GHB free acid was developed and applied. An extension of this study included preparing for use as a standard reference material, small amounts (less than 10 mg) of GHB free acid. 3 tables, 12 figures, and 18 references