The authors report on the fabrication and characterization of near infrared fluorescent nanofibers. The nanofibers are composed by an organic dye dispersed in a poly(methylmethacrylate) inert matrix and realized by electrospinning. They exhibit diameters down to 70 nm, with average values in the range of 170-480 nm, depending on the process parameters, and photoluminescence emission peaked at 865 nm. The temporal behavior of the emission under ultraviolet excitation in air can be described by an oxygen diffusion model with a characteristic time tau in the range of 400-1200 s, depending on the fiber size, which correspond to a photostability longer than (0.4-1.2)x10(5) excitation laser pulses. These results open the way for large volume and cost-effective realization of infrared-emitting nanofibers, which are promising candidates as nanoscale infrared light sources. (c) 2007 American Institute of Physics.