Embodiments in accordance with the present invention encompass compositions containing a latent organo-ruthenium carbide catalyst, a photoactive acid generator or a thermally active acid generator and a photoactive compound along with one or more monomers which undergo ring open metathesis polymerization (ROMP) when said composition is exposed to a suitable radiation (or heat) to form a three-dimensional (3D) object. The three-dimensional objects made by this process exhibits improved mechanical properties, particularly, high distortion temperature, impact strength, elongation to break, among others. Accordingly, compositions of this invention are useful as 3D inkjet materials for forming high impact strength objects of various sizes with microscale features lower than 100 microns, among various other uses.