Determination of a low level 237Np in environmental samples was performed by various techniques: i) a direct gamma-ray spectrometry, ii) an alpha-particle spectrometry that followed pre-separation of neptunium radioisotope(s) by ion-exchange or extraction chromatography and iii) pre-separation radiochemical neutron activation analysis. The methods used were applied to various reference materials with inorganic and organic matrix as well as to a wide range of neptunium content. The results were compared with reference and literature values. •Determination of low-level Np-237 is described.•Three different techniques for decomposition of samples were compared.•Separations were done with ion exchange and extraction chromatography.•γ-ray spectrometry, α-particle spectrometry and pre-separation RNAA were compared.