1919, coined by W.H. Smyth as a name for a new system of government by technical experts, from techno- + -cracy.
William Henry Smyth, a distinguished engineer of Berkeley, California, wrote at the close of the war a series of thoughtful papers for the New York magazine "Industrial Management", on the subject of "Technocracy". His thesis was the need of a Supreme National Council of Scientists to advise us how best to live, and how most efficiently to realize our individual aspirations and our national purpose. ["The Bookman," March 1922]
There is an earlier use from 1895 in reference to the medical profession.