During the 1st World War KPI main building used for defense purposes was placed in a room of food and dressing station evacuation hospital. Since August 1914 all of its middle part, except the library premises, occupied hospital. October 20 in the hall, equipped with 140 beds, there was a big fire, resulting in burned floors and walls, collapsed ceilings. The hospital was closed in September 1915, but the militia were in the room.
Workshop and chemical laboratory corps were transferred to the Military Industrial Committee and worked on defense. Rocket workshop were organized and pharmaceutical laboratory. On September 1, 1915 in the main building workshops were organized for aviation, which began to produce propellers, parts of aircraft, airplanes started production of the "Albatross" and others. In 1916 part of the building used for the expansion of aviation and automotive department of mechanical workshops. During 1917 there were placed pyrotechnics workshop, the headquarters of the 1st Polish Infantry Regiment, 5th Office of Aviation Park. At the end of 1917 - beginning of 1918 - the headquarters of the Red Workers' groups. Later, the Institute released gradually and repaired. In the years 1922-23 restored assembly hall.