A compact source of monoenergetic X‐rays generated via Compton backscattering is under development at SLAC. It consists of a Photoinjector operating at 11.424 GHz, a stage of post acceleration using a 1.05 m long high gradient accelerator structure and an interaction chamber where a high power (TW), short pulse (sub‐ps) infrared laser beam with a high quality focused electron beam are brought into collision. Successful completion of this project will result in the capability of generating a monoenergetic X‐ray beam, continuously tunable from 20 – 85 keV. All components have been installed and initial testing has commenced. We are currently generating and accelerating an electron beam up to the accelerator and measuring the essential beam parameters, i.e., quantum efficiency, emittance, energy and stability. The latest test results will be presented together with a description of the beamline components and laser system. © 2003 American Institute of Physics