A solvent extraction separation of uranium with a new crown hydroxamic acid 5, 14-N, N'-hydroxyphenyl-4, 15-dioxo-1,5,14,18-tetraaza hexacosane (NHDTAHA) in the presence of cerium, thorium and lanthanides is described. The uranium is extracted with chloroform solution of NHDTAHA and the extract is directly used for GS-AAS measurements. The detection limit is 0.01 ppm with a sensitivity of 20 ng/0.005 absorbance of uranium. The extraction constants of uranium crown hydroxamic acid complexes are determined. The selectivity factors (K u r a n y l /K n + M ) for uranium crown hyrdoxamate evaluated by comparing the K u r a n y l with the stability constants for competing metal cations (K n + M ) and anions (K n A - ) and were found to be remarkably large. Uranium is preconcentrated and also determined spectrophotometrically. The molar absorptivity is 1.0x10 4 l - 1 mol - 1 per cm at 390 nm and system obeys Beer's law in the range 2.0-30 ppm of uranium. Uranium has been determined in standard and environmental samples.