Palladium(0) nanoparticles supported on a polymeric membrane, CA/Pd(0), were found to be a highly efficient “dip catalyst” (heterogeneous catalyst) for Suzuki–Miyaura cross-coupling reactions. Iodo-, bromo- and electron-poor chloroarenes coupled with phenylboronic acid under eco-friendly conditions (i.e., phosphine-free and with water as the solvent) to give excellent yields. The CA/Pd(0) was prepared initially via the synthesis of Pd(0) by hydrogen decomposition of Pd(acac)₂ dissolved in BMI·BF₄ ionic liquid at 75 °C for 1.0 hour to yield a black suspension (nanoparticles with a diameter of 2.7 ± 0.4 nm). These nanoparticles were washed with acetone and dried under reduced pressure. The Pd(0) nanoparticles were subsequently added to a cellulose acetate solution with acetone to generate the CA/Pd(0) polymeric membrane. The CA/Pd(0) “dip catalyst” was characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron-dispersive spectroscopy (EDS) and transmission electron microscopy (TEM).