Parahydrogen-induced polarization of a 13 C-labelled target substance is achieved by catalytic hydrogenation of a suitable precursor with para-enriched hydrogen gas (pH 2 ). The proton pairs in the reaction product acquire a high degree of nuclear singlet order. The non-magnetic nuclear singlet order is con- -succinic acid. The spin-spin couplings have been reported previously , except for those involving deuterium, which are estimated. The labile protons are ignored.