Mid-infrared light-emitting diodes (LEDs) operating in the 3.3-4.5 mum wavelength range at room temperature are produced on the basis of InAsSbP/InAsSb heterostructures. The photoluminescence of InAsSb layers and electroluminescence properties of LEDs are investigated. LEDs light-current characteristics are also studied. Fabricated were LEDs of (**)A(**) and B-**(**) type. (**)A(**) being preferential for currents in excess of 200 mA. and **B** being better for the current range 0-200mA. When operating at 5% duty Cycle, at room temperature wavelength lambda=3.4mum the pulse power of the diodes is measured as 1.2mW under 1.3A drive current. (C) 2002 Elsevier Science B.V. All rights reserved.