Solvent extraction, using Alamine 304-1 for loading (extraction) and ammonia for stripping, was used for selectively recovering molybdenum from acid wash liquor produced by a Mo processing plant. The results showed that the extraction could be completed in 3 stages, using Alamine 304-1 as the extractant (10%, v/v in Anysol 150 diluent), with almost all the Mo(VI) recovered from an acidic sulfate wash liquor, containing 10-15 g/L Mo(VI), 10 g/L Cu(II) and 2 g/L Fe(III), using an O/A volumetric ratio of 3:2. Using ammonia (12.5%, w/v), at an O/A ratio of 5:1, all the Mo(VI) from an Alamine liquor containing 17.5 g/L Mo could be removed in one strip, yielding a solution with 87.0 g/L Mo(VI). High purity (>99-9%) MoO(3) and CaMoO(4) were produced from this pure liquor via an intermediate hydrate precipitate (MoO(3) center dot H(2)O). The study also showed that understanding the stability and speciation of various soluble and solid Mo species are essential for the development of an efficient recovery process. (C) 2008 Elsevier Ltd. All rights reserved.