Abstract A xenon filled single anode wire chamber with delay line readout has been constructed for use in powder X-ray crystallography using 8–20 keV X-rays. The entire chamber including the anode wire and the delay line which forms part of the cathode plane is a section of a circular arc whose center is the powder specimen. The anode wire - 38 =mum goldplated tungsten - is suspended in a circular arc by the interaction of a current flowing through it and a magnetic field provided by two permanent magnets, above and below the wire, extending along the active length of the chamber. When filled with xenon to 3 atm the chamber has uniform sensitivity in excess of 80% at 8 keV and a spatial resolution better. than 0.3 mm.