For the first time in the history of high energy astronomy , a large CdTe gamma-ray camera is operating in space .
ISGRI is the low-energy camera of the IBIS telescope on board the INTEGRAL satellite .
This paper details its design and its in-flight behavior and performances .
Having a sensitive area of 2621 cm ^ { 2 } with a spatial resolution of 4.6 mm , a low threshold around 12 keV and an energy resolution of \sim 8 % at 60 keV , ISGRI shows absolutely no signs of degradation after 9 months in orbit .
All aspects of its in-flight behavior and scientific performance are fully nominal , and in particular the observed background level confirms the expected sensitivity of 1 milliCrab for a 10 ^ { 6 } s observation .