In this work, the authors prepared a novel magnetic photocatalyst by grafting of Preyssler-type polyoxometalate, H 14 [NaP 5 W 30 O 110 ] onto Fe 3 O 4 nanoparticles via an internal layer of silver nanoparticles. The obtained nanocomposite has been characterised by electron dispersive X-ray, transmission electron microscopy and scanning electron microscopy. The activity of the synthesised nanomagnetic photocatalyst was tested by the photocatalytic decolourisation of rhodamine B under UV light irradiation in the study's designed reactor. It was found that, compared to pure Preyssler, decolourisation of rhodamine B was occurred four times faster using the synthesised magnetic nanocomposite with easy separation. The magnetic nanocatalyst was separated after ending the reaction and recycled. It just showed 2-3% decrease in catalytic activity after four recycling.