Determination of molybdenum in different kinds of environmental samples is often a challenging task for analysts. Its concentration is usually very low and the sample matrix may cause serious interferences during measurement. Therefore, preconcentration and separation methods should be used to solve these problems and render more sensitive, accurate and interference-free determination. Recent developments in sample treatment, such as solid phase and liquid-liquid extraction as well as coprecipitation are presented, including flow-based methodology. In addition, important extension and improvements in analytical methods for determinations of molybdenum are updated. Some examples of speciation analysis are also presented.