FIELD: materials for infrared (IR) fibre optics. SUBSTANCE: invention is related to silver halide light guides. The method for producing silver halide fibres based on nanoceramics of the AgCl_0.25Br_0.75 - AgI system includes computer simulation using the finite element method to determine the extrusion parameters - temperature, plunger pressure on the silver halide billet and the speed of movement of the billet through the spinneret when obtaining fibres, while nanoceramic workpiece with a diameter of 8.0 mm, a height of 16.0 mm based on two solid solutions of a hexagonal phase of the wurtzite, P6₃mc structure, and a cubic phase of the NaCl, Fm3m structure, composition AgCl_0.25Br_0.75, additionally containing silver iodide at a certain ratio of ingredients, is heated to 170°C, exposed for 60 minutes to warm up the workpiece and at a plunger pressure of 1200 MPa and its vibration on the workpiece with a frequency of 50 Hz, an amplitude of 50 mcm, which ensures its movement at a speed of 0.6 mm/min to form a silver halide light guide with a diameter of 450 mcm, length of 5 m with a defective surface in form of transverse grooves with a depth of 5 mcm, a width of 10 mcm and a step of 80 mcm. EFFECT: invention enables production of radiation-resistant silver halide fibres with a defective structure, transparent in the mid and far IR ranges from 3.0 to 27.0 mcm, which makes it possible to detect the spectra of chemical compounds when determining chemicals with high sensitivity up to 0.0005 mol/l in a wider spectral range. 1 cl, 3 dwg, 3 ex.