Abstract: There is described a method for the preparation of a hyperpolarised agent, wherein said agent comprises at least one —N?, —O? or —S? moiety (optionally protonated) and a secondary binding site; said method comprising: (i) preparing a fluid containing a polarisation transfer precatalyst and parahydrogen; (ii) introducing a co-ligand to interact with the transfer precatalyst to form a polarisation transfer catalyst; (iii) applying a magnetic field or radio frequency excitation to (ii), such that hyperpolarisation is transferred from parahydrogen to a target molecule; (iv) introducing a target molecule containing at least at least one —N?, —O? or —S? moiety, in conjunction with a secondary binding to form a hyperpolarised agent; wherein the co-ligand is selected from the group consisting of one or more of a sulfoxide, a thioester, a phosphine, an amine, CO, an isonitrile and a nitrogen heterocycle.