We report on a luminescent phenomenon in Sm3+-doped Sr3Sn2O7 afterglow phosphor XRD photoluminescence afterglow emission spectra and long-lasting phosphorescence decay curve are used to characterize this phosphor After irradiation by a 267-nm UV light for 5 min the Sm3+-doped Sr3Sn2O7 phosphor emits intense reddish-orange emitting afterglow from the (4)G(5/2) to H-6(f) (J=5/2 7/2 9/2) transitions and its afterglow can be seen with the naked eye in the dark clearly for more than 1 h after removal of the excitation source Photoluminescence spectra reveal that the reddish-orange light-emitting long-lasting phosphorescence originate from the mixture of Sm3+ characteristic transitions The afterglow decay curve of the Sm3+-doped Sr3Sn2O7 phosphor contains a fast decay component and another slow decay one The possible mechanism of this reddish-orange light-emitting LLP phosphor is also discussed based on the experiment results (c) 2010 Elsevier BV All rights reserved