GaInAsPSb is a new narrow gap semiconductor material, which is suitable for the fabrication of semiconductor light sources for the mid-infrared spectral range. Unique physical properties of the alloy are discussed and its advantages for mid-infrared optoelectronic devices are considered. Liquid phase epitaxy (LPE) growth conditions for GaInAsPSb homogeneous high crystal quality layers lattice-matched onto GaSb substrates were determined. Spectra of photoluminescence (PL) emission were investigated. Homojunction p-i-n light-emitting diodes (LEDs) based on this pentenary alloy were fabricated and electroluminescence (EL) peaking near 4.0 μm at room temperature was observed.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.