The TiO2 nanoparticle photocatalyst was used to decolourise industrial date syrup. The effect of TiO2 concentration (1 and 4% w/v), UV power (15 and 30 w) and processing time (12 and 48 h) on date syrup characteristics was investigated using a factorial design. The colour, turbidity, sugar content, total phenolic compounds, ash content and mineral (K, Na, Ca, Mg and Fe) of date syrup were analysed. The results demonstrated that using TiO2 nanoparticle as a photocatalyst for the decolourisation of date syrup is an effective and promising method. Colour in all treatments was significantly (P < 0.05) reduced between 30 and 53% in comparison with the initial date syrup (491 000 IU), and the reduction was even higher for date syrup turbidity (between 47 and 75%). The result showed that the process condition significantly affected the colour and turbidity reduction. On the basis of the result, the best treatment was TiO2 4%, 15 w and 48 h. Under this condition, date syrup colour, turbidity, ash content, sugar content reduced by 52%, 61%, 13% and 9%, respectively.