The thermo-oxidative behavior of unformulated (unfilled) samples of epoxy coatings has been studiedat five temperatures ranging from 70◦C to 150◦C. Two epoxy networks based on diglycidyl ether ofbisphenol A (DGEBA), respectively, cured by jeffamine (POPA) or polyamidoamine (PAA) were compared.Infrared spectrophotometry (IR), differential scanning (DSC) and sol-gel analysis (SGA) were used tomonitor structural changes.Thermal oxidation leads to carbonyl and amide formation in both systems. POPA systems appear moresensitive to oxidation than PAA ones. Thermal oxidation leads to predominant chain scission as evidencedby the decrease of glass transition temperatures (Tg) and increase of sol fraction.