This work reports hydrogen adsorption on C3H3–TM (TM = Sc, Ti) organometallic compounds using second-order Moller–Plesset perturbation theory method. Two types of organometallic compounds are considered viz. transition metal-capped and transition metal-inserted. Maximum five and four hydrogen molecules were adsorbed on Sc-capped ScC3H3 and Ti-capped TiC3H3 complexes, thereby giving gravimetric hydrogen uptake capacity of 10.71 and 8.5 wt%, respectively. The gravimetric H2 uptake capacity 10.71 wt% of ScC3H3 complex is higher by 1.41 wt% than that of Sc-capped ScC4H4 organometallic complex reported earlier. The hydrogen uptake capacity 8.5 wt% of TiC3H3 is in between the uptake capacity of 6.61 and 9.1 wt% shown by Ti-capped TiC5H5 and TiC4H4 organometallic complexes, respectively. The Sc-capped and Sc-inserted ScC3H3 adsorb same number of H2 molecules whereas Ti-inserted TiC3H3 complex adsorbs less number of H2 molecules than that of Ti-capped TiC3H3 complex. Nature of interactions between different molecules in hydrogen-adsorbed complexes is studied. The binding energy per H2 molecules differ by about 0.1 eV in transition metal-capped and transition metal-inserted structures.