Kohn was born in Manhattan, attended Columbia University, and spent four years at the Ecole des Beaux-Arts in Paris, from 1891 through 1895.
Instead of the school's broad window facing Central Park, the meeting house has wide, limestone expanses, like a mausoleum, and simply, blocky detailing."
(Stern et al.) He worked in association with his brother, Victor H. Kohn, who died in New York, 4 May 1910, aged thirty-eight.
In 1918 he was a founding member of the Technical Alliance, organized for the purpose of undertaking an energy survey of North America, for the reconsideration of the workings of the entire social system; their work was continued by Technocracy Inc. From 1917 through the early 1950s Kohn collaborated, formally and informally, with fellow architect Charles Butler.
The west end of Emanu-El, facing Central Park, is a single vastly-scaled entrance porch, infilled with stained glass under a round-headed arch.