Homogeneous catalysts are substances that speed up chemical reactions while being in the same phase, or state, as the reactants. Typically, these catalysts are dissolved in a solution, allowing them to interact uniformly with the reactants. This uniformity often leads to more efficient reactions and can help lower the energy required for the process. One common example of a homogeneous catalyst is transition metal complexes, which are often used in organic reactions. These catalysts can facilitate various processes, such as hydrogenation and polymerization, by providing an alternative reaction pathway with a lower activation energy.