A new technique of neutron energy measurement not requiring neutron collimation is described. The method employs the nuclear reaction Li6(n,&agr;)H3(Q=4.64 Mev) observed within photographic emulsions impregnated with enriched Li6. Results on monoenergetic neutrons indicate a resolution of at least ±0.1 Mev in the region studied (from thermal energies up to 1.3 Mev). To extend the method to measurement of continuous neutron spectra, both the excitation function and the angular distribution of the Li6disintegration process should be known. However, for immediate practical application, the method may be calibrated with a well‐known spectrum. The Li6technique is particularly well suited to energy measurements on neutrons within a material medium where perturbations introduced by the detector must be minimized and where collimation is clearly impossible.