This study examined the effect influence of various factors on the extraction of Pd(II) to develop a new liquid-liquid extraction mechanism for the selective separation of palladium(II) from its acidic chloride solutions using 4-aroyl-3-phenyl-5-isoxazolones (HA), such as 3-phenyl-4-(4-fluorobenzoyl)-5- isoxazolone (HFBPI), 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) and 3-phenyl-4- (4-toluoyl)-5-isoxazolone (HTPI). The extraction strength of Pd(II) with HA were in the following order: HFBPI > HPBI > HTPI, which is opposite to that observed with their pKa values. HPBI was used to separate Pd(II) from Pt(IV), Ni(II) and Rh(III) metal ions and calculated their separation factors (S.F.) were followed in the order: Pd/Ni (40±0.4) > Pd/Pt (25±0.2) > Pd/Rh (15±0.3 > Rh/Ni (2.7±0.3) > Pt/Ni ≈ Rh/Pt (1.7±0.2). The loading and striping of Pd(II) (1.12×10-4 mol L-1) were also examined using 1.0×10-3 mol L-1 HPBI in CHCl3 and 1.0 mol L-1 HCl, respectively. The results demonstrated that the maximum (97.5%) extraction and desorption (89%) of metal required at least 3.0 cycles. The developed method was applied successfully to the separation of palladium from synthetic water samples.