Honey is a complex mixture of different carbohydrates in which fructose and glucose are the most abundant. The quantities of these monosaccharides are believed to vary during the aging of honey according to the chromatographic studies reported. Since the effects of heating are similar to those induced by natural aging, two types of unifloral honeys (heather Calluna vulgaris and rosemary Rosmarinus officinalis L.) were each heated at 45°C and 60°C, for specified lengths of time.Quantification of glucose and fructose, as well as the ratio glucose/fructose, was attempted by HPLC, liquid state NMR and FTIR-ATR (attenuated total reflectance) and the results compared. All three techniques showed glucose and fructose as the major components in honey and NMR and HPLC showed that the latter is the most abundant in both varieties. NMR enabled the identification of the major anomers of the two monosaccharides along with some oligosaccharides present in small quantities. The oligosaccharides detected by HPLC were: turanose, maltose, trehalose and isomaltose, as well as melizitose in rosemary honey. Quantification of these oligosaccharides could only be carried out by HPLC.The effects of heating on the sugar composition were clear in the NMR spectra, indicating that the decrease in fructose content is accompanied by a slight increase in glucose content. This change was more pronounced in the rosemary honey. HPLC results showed a significant increase of the oligosaccharides. The use of ATR cell enabled good quality FTIR spectra to be obtained for all samples. Due to the strong signal overlap observed in the region of interest (1500-800 cm - 1 ), no individual signals were assigned but one particular intensity ratio was found to depend, particularly for the rosemary variety, on the temperature and time of heating. Studies are currently under way to explore the use of such ratio measurements as an indicator of glucose/fructose ratios in honey samples.