In order to produce human milk fat substitutes (HMFS) that mimic human milk fat several studies have been carried out using immobilized lipases as catalysts. The successful production of HMFS can be impeded by their high susceptibility to oxidative deterioration [1]. Differential Scanning Calorimetry (DSC) technique coupled with a pressure cell have the potential to be used as an accelerated thermal method to determine oil quality. It has previously been successfully used for human milk fat substitutes and other fat products for quality assessment [2]. The aim of current study was to evaluate the oxidative stability of human milk fat substitutes, synthesized by enzymatic interesterification of a blend of lard and milk thistle oil, using Pressure Differential Scanning Calorimetry (PDSC) and Fourier Transform Infrared Spectroscopy (FT-IR). The enzymatic reactions were carried out at 70°C for 2, 4 and 6 hours, respectively. A commercially immobilized 1,3-specific lipase, Lipozyme RM IM, obtained from Rhizomucor miehei was used as a biocatalyst. Raw experimental data were recorded with use of the differential scanning calorimeter (DSC Q20 TA Instruments) equipped with a high-pressure cell (PDSC). Samples of oil were placed in the aluminium pan, filled with oxygen, being pressurized in an isobaric module (1400 kPa) with temperature set on 120°C. The oxidative induction time was obtained from the PDSC curves. In addition the IR spectra registered in the classic range (4000 – 400 cm-1) were used to differentiate the samples of interesterified fats. The results confirm that the induction time obtained from PDSC measurements can be used as parameters for the assessment of the resistance of HMFS to their thermal-oxidative decomposition. Obtained HMFS were characterized by lower induction time that initial fats.