Theodore Adrian de Kruijff was born in New York City, New York, on July 26, 1891 the son of Theodore E. and Mary de Kruijff. He attended New York City public schools.
In anticipation of entering the European War, de Kruijff joined the Curtiss aviation school at Buffalo, New York where he earned a pilot's license. His Curtiss aircraft was involved in a crash while he was flying with another student. de Kruijff broke his leg in the fall. When he recovered, he continued to fly at Newport News, Virginia until January 1917 when he left for France to join the Lafayette Flying Corps.
On 20 March 1917, de Kruijff enlisted in France's Service Aeronautique. From 20 March to 4 December 1917, he attended the aviation schools at Avord, Pau, Cazeaux, and the G.D.E. Despite much trouble from his injured leg, de Kruijff received his military brevet on the Nieuport on 6 August 1917.
From 6 December 1917 to 21 May 1918, Caporal de Kruijff served at the Front with Escadrille N. 158. On 21 May, de Kruijff was commissioned a Second Lieutenant in the U.S. Air Service.
From 6 June to 5 July 1918, Lieutenant de Kruijff was assigned as a ferry pilot at the American Acceptance Park, Orly. From 5 July to 1 November 1918, he served at the American Aviation Instruction Center, Romorantin.
Lieutenant de Kruijff died of pneumonia at the American Red Cross Hospital #1 in Neuilly on 6 November 1918. He was buried at the A.E.F. Cemetery #34, Paris. In June of 1928, his remains were transferred to the Lafayette Flying Corps monument in France.
[Source: "The Lafayette Flying Corps: The American Volunteers in the French Air Service in World War One," by Dennis Gordon. Schiffer Military History, Atglen, PA: 2000. Page 274.]