Hydrogenation of DMAD over cationic Rh catalysts is known to proceed via syn-addition of two hydrogen atoms to the carbon-carbon triple bond, giving predominantly dimethyl maleate, the cis-conformer of the product molecule. The latter possesses a carbon-carbon double bond and can be hydrogenated further to dimethyl succinate. Both the spectra (Fig. ) and the kinetics (Fig. , , are in agreement with this reaction mechanism . At the same time, it should be noted that for hyperpolarized molecules the nuclear spin relaxation processes mentioned above significantly affect the integrated NMR signal intensities which, as a result, are not proportional to respective concentrations. Therefore, a quantitative analysis of the kinetic traces presented in Fig. , 5 is not trivial, and is beyond the scope of this study. Nevertheless, some useful information on this reacting system can be obtained even from a qualitative data analysis.