Magnetism of Pr ordering in 2-CuO2 layer high Tc superconductor system are discussed. The Pr magnetic properties for the TlBa2PrCu2O7-δ and related Tl(Ba,Sr)2PrCu2O7-δ and TlBa2(Pr,Ca)Cu2O7-δ compounds with the tetragonal Tl(1212) structure are reported through low temperature heat capacity, magnetic susceptibility, x-ray and neutron diffraction measurements. The anomalous high antiferromagnetic Néel temperature TN(Pr) is the result of strong hybridization between the Pr-4f orbitals and adjacent oxygen-2p orbitals in the CuO2 layers.