The aim of the present study was to investigate the effects of palm olein (PO) addition on the quality characteristics of sunflower oil (SFO) during frying of potato pieces. The blends were prepared in the volume ratios of 20:80 (PO:SFO, PSF1) and 40:60 (PO:SFO, PSF2). Refractive index, free fatty acid content, peroxide value, p-anisidine value, TOTOX, viscosity, specific extinction, polar compounds, food oil sensor value, colour, and polymer content of the oils all increased, whereas iodine value and C 18:2 /C 16:0 ratio decreased as frying progressed. The percentage of linoleic and linolenic acids tended to decrease, whereas the percentages of palmitic and oleic acids increased. Based on the most oxidative stability criteria investigated, PO addition led to a slower deterioration of SFO at frying temperature. Blend PSF2 showed better frying performance compared to PSF1. However, higher amounts of free fatty acids and higher colour units were both detected in the blends compared to pure SFO at the end of frying. It appears that proper blending of highly unsaturated SFO with PO can result in oil blends that could meet nutritional needs with improved stability for domestic cooking and deep-frying.