Folate is a vitamin group consisting of water-soluble vitamers, which differ by the nature of the substitution (N5 or N10), the oxidation degree and the length of the glutamate tail. A sufficient supply is effective in reducing neural tube defects, cardiovascular and neurodegenerative diseases. Green vegetables are a major source of folates in European diets. They are most often consumed after processing (industrial or cooking), which can lead to folate losses due to heat degradation and oxidation. The main folate vitamer studied in model solution or during industrial processing still is 5-methyltetrahyrofolate. Therefore, we aimed to determine the kinetics parameter and the degradation products for two other vitamers abundant in green vegetables, namely 5-formyltetrahydrofolate (5-HCO-H4folate) and 10-formylfolic acid (10-HCO-PteGlu), during heat treatment and in the presence of an oxidation catalyst. Kinetics were carried out in ammonium buffer pH 5 and 7 and in water at room temperature, 85°C and 100°C. Kinetics were also carried out in the presence of hydrogen peroxide. Samples were collected for 4 hours and analysed by LC-MS and FT-ICR. Kinetics were modelled, degradation rate constant (k) and activation Energy (Ea) were determined according to the first order equation. As compared with 5-HCO-H4folate, 10-HCO-PteGlu remained quite stable over 4 hours with a maximum of loss of circa 50% in maximum. 5-HCO-H4folate was highly degraded during the kinetics. The main factors involved in losses during the kinetics were the temperature and the concentration of hydrogen peroxide. Degradation and transition products of 5-HCO-H4folate were identified by LC-MS as 10-HCO-PteGlu, methenyltetrahydrofolate, and para-aminobenzoyl glutamic acid. Further compounds were detected by LC-MS and tentatively identified by FT-ICR. Our study enabled to identify the degradation kinetics constant and degradation compounds of formyl folates, which is relevant for understanding folate degradation mechanisms during vegetables processing.