A simple, sensitive and selective method for the spectrophotometric determination of Pd(II) has been developed. Palladium (II) reacts with 1,10-phenantroline and 4-nitrobenzenediazobenzene (Cadion A) in the presence of the non-ionic surfactant Peregal 0 to form a stable complex. The maximum absorption of the complex is at 490 nm, its apparent molar absorptivity is 8.01 × 104L · mol−1· cm−1. The composition of Pd : Phen : Cadion A is 1 : 1 : 2. Beer's law is obeyed for Pd in the range of 0–20 μg/25 mL, with EDTA and sodium potassium tartrate as masking agents, common ions do not interfere. The method has been used in the determination of palladium in Pd containing catalysts without separation.