Abstract: There is described a method for the preparation of a hyperpolarised target molecule, wherein said molecule comprises at least one —OH, —NH or —SH moiety, via proton exchange from a polarisable molecule, said method comprising the steps of: (i) preparing a fluid containing a transfer catalyst; parahydrogen; and a polarisable molecule containing at least one exchangeable proton, such as, an —OH, —NH or —SH moiety; (ii) applying a magnetic field or radio frequency excitation such that hyperpolarisation is transferred from parahydrogen to the polarisable molecule when bound to the magnetisation transfer catalyst; (iii) separately or simultaneously introducing a target molecule, wherein said target molecule contains at least one —OH, —NH or —SH exchangeable proton, enabling hyperpolarisation transfer via proton exchange with the polarisable molecule.