Processes for the preparation of nanopalladium (0) catalysts are disclosed. In some embodiments, the nanopalladium (0) catalysts may be reusable. In some embodiments, the nanopalladium (0) catalysts may be heterogeneous. Nanopalladium (0) catalysts may be employed for preparing coupling products by C—C bond formation through reaction of haloarenes in the presence of base. Haloarenes used in the coupling reaction may include chloroarenes that are typically unreactive. The use of heterogeneous nanopalladium catalyst may preclude the presence of trace amounts of palladium in the final coupling product.