The aim of the study was to investigate the changes in the essential oil constituents of coriander and caraway when treated with UHP and/or elevated temperatures in a helium atmosphere. The UHP and/or heat treatment was conducted for 30 mins at 800 MPa, the temperature range was 60-121°C. The changes in the volatile oil content did not exceed 5% in all the treatment conditions. The pressure and temperature processing altered the composition of the essential oils of spices, which was examined using the GC-MS method. The most important sensory compounds, namely linalool in coriander oil and carvone in caraway oil, were not essentially changed after the processing. The final oil composition was different in the pressurised and not pressurised samples heated at the same temperature.