The invention provides a method for the purification of 227 Th from a mixture comprising 227 Th and 223 Ra, said method comprising: i) preparing a first solution comprising a mixture of 227 Th and 223 Ra ions dissolved in a first aqueous buffer ii) loading said first solution onto a separation material such as a strong cation exchange resin iii) eluting 227 Th from the separation material, whereby to generate a second solution comprising 227 Th iv) Optionally rinsing said separation material using a first aqueous washing medium The invention additionally provides a method for forming a radio pharmaceutical comprising complexing the purified 227 Th, the pharmaceutical product and its use in treatment of disease such as cancer and a kit for generation of such a product.
