A highly sensitive, simple and rapid in-tube ultrasonic and air-assisted liquid-liquid microextraction (IT-UAA-LLME) coupled with flame atomic absorption spectrometry was developed for preconcentration and determination of palladium (Pd) in soil and water samples. The effective parameters were optimized by the Plackett-Burman (P-B) and Box-Behnken design (BBD) methods. Under the optimum conditions, the calibration graph was linear over the range of 5-800 mu gL(-1) (R-2 = 0.998). Detection limit, relative standard deviation (RSD) and the enrichment factor were 0.94 mu gL(-1), 2.64% (n = 7, C = 40 mu gL(-1)) and 156, respectively. The proposed method was successfully applied for the determination of trace amounts of Pd in the soil and water samples.