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This paper describes synthesis of Pd-containing catalysts of Suzuki cross-coupling based on amino-functionalized hyper-cross-linked polystyrene at variation of Pd precursor nature (PdCl₂, PdCl₂(CH₃CN)₂, or PdCl₂(PhCN)₂). The investigation of the influence of palladium oxidation state (Pd(II) or Pd(0)) and form (Pd_n clusters or Pd nanoparticles) on the rate of Suzuki cross-coupling of 4-bromoanisole and phenylboronic acid is discussed. Developed catalysts are shown to allow achieving conversion of 4-bromoanisole higher than 98% under mild reaction conditions. Independently of the precursor nature, Pd(II) is mainly responsible for observed catalytic activity. However, preliminary reduction of catalysts with H₂ results in formation of a large number of Pd_n clusters, the contribution of which in the Suzuki reaction becomes predominant.