The direct incorporation reaction of Pd(II) into α, β, γ, δ-tetraphenylporphine-trisulfonate(TPPS) was very slow and had no practical value. However, in the presence of 2 × 10-5, to 2 × 10-4 mol dm-3 of L-ascorbic acid, the reaction was accelerated extensively to form TPPS-Pd complex within 7 minutes under boiling condition at pH range of 2.8 to 7.0. The complex once formed was stable over pH 2 to 11, and its absorbance was constant for 12 h. The soret bands of TPPS and TPPS-Pd at pH 2.5 were located at wavelength of 434 run (e=5.0 × 105) and at 411.6 nm (e=2.76 × 105), respectively. Thus, the both or one of the bands can be applied for the spectrophotometric determination of 10 ng levels of Pd(II): take 15 cm3 of sample solution containing (1 6) μg of Pd(II) into 50 cm3 beaker and add 6 cm3 of 1 × 10-5 mol dm-3 TPPS solution, 1 cm3 of 1×10-3 mol dm-3 L-ascorbic acid solution and 1 cm3 of 1 mol dm-3 acetic acid solution (pH 3.0). Heat the mixture for 8 minutes and allow to cool. Add 1 cm3 of 1 mol dm-3 monochloroacetic acid, dilute to 25 cm3 with water (pH 2.5) and measure the absorbance at 411.6 nm and/or 434 nm against reagent blank.500 μg of Ba2+, Cd2+, Ni2+, Pb2+ and VO3-, 50 μg of Al3+, Ca2+, Co2+, Cr3+, Ga3+, Mg2+, Mn2+, Mo6+, VO2+, W6+ and Zn2+, and 5 μg of Ag+, Fe2+, Fe3+, In3+, Pt2+ and Sn2+ did not interfered with the determination. However, 5 μg of Cu2+ and Hg2+ interfered. At 411.6 nm, Beer's law was confirmed over 0 250 ng Pd2+ cm-3 and the sensitivity for A =0.001 was 0.494 ng Pd2+ cm-2.