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The molecular structure of the mineral andersonite, a uranyl tricarbonates, has been studied by Raman microscopy at 298 and 77 K and ATR infrared spectroscopy. Raman bands are observed at 3558, 3510 and 3415 cm-1 and infrared bands at 3559, 3502, 3388, 3270 and 3120 cm-1 enabling estimates of the hydrogen bond distances of 2.98, 2.91, 2.80, 2.77, 2.707 and 2.701 Å to be estimated. The wide range of values shows the water molecules are not equivalent in the structure of andersonite. Two well resolved Raman bands at 1092 and 1080 cm-1 assigned to the ν1 symmetric stretching modes of the (CO3)2- units prove the existence of two non-equivalent carbonate units. A single peak at 832 cm-1 resolvable into two bands at 833 and 831 cm-1 is attributed to the overlap of the symmetric stretching modes of the (UO2)2+ units and the ν2 bending modes of the (CO3)2- units. The ν4 in-plane bending region is characterised by three Raman bands at 745, 726 and 698 cm-1 confirming the loss of symmetry of the carbonate anion and the non-equivalence of the carbonate units. Raman spectroscopy at 298 and 77 K assists in the assignation of bands to the structure of andersonite