Glycolaldehyde is a small sugar-like molecule that is readily formed by the thermochemical fragmentation of carbohydrates and it has similar physico-chemical properties to sugars. Current methods for the analysis of glycolaldehyde comprise low-selective and time-consuming chromatographic or spectroscopic techniques, such as high-performance liquid chromatography, nuclear magnetic resonance spectroscopy and Fourier-transform infrared spectroscopy. The aim of this study was to develop and validate a quick method for quantifying glycolaldehyde in aqueous solutions using liquid injection gas chromatography-mass spectrometry. Various chromatographic parameters were optimized to obtain a baseline separation of glycolaldehyde from other polar matrix components in the mixture, as well as achieving a high peak symmetry, low band broadness and high resolution. The final gas chromatographic method consists of: a hundred-fold dilution of the sample in acetonitrile, an initial oven temperature of 80 °C, a mobile phase flow rate of 2 ml min^-1, a split ratio of 50:1, a thermal gradient of 60 °C min^-1, a final temperature of 220 °C, an injection volume of 1 μl, and the use of free-fatty acid polyethylene glycol as the capillary stationary phase. The GA concentrations were determined through internal, external, standard addition, and internal-standard-corrected standard addition calibration curves. The developed method is rapid (5.3 min), accurate (>90%), and precise (intra-day, inter-day and inter-laboratory precisions are all <4% relative standard deviation), with a limit of detection and a limit of quantification of 0.104 and 0.315 g L^-1, respectively. This method can be further optimized for the analysis of other carbohydrate-related mixtures in aqueous solutions for both quantification and identification purposes.