Kinematic edges of cascade decays of new particles produced in high-energy collisions may provide important constraints on the involved particles' masses. For the exemplary case of gluino decay g˜→qq¯χ˜ into a pair of quarks and a neutralino through a squark resonance, we study the hadronic invariant mass distribution in the vicinity of the kinematic edge. We perform a next-to-leading order calculation in the strong coupling αs and the ratio of squark width and squark mass Γq˜/mq˜, based on a systematic expansion in Γq˜/mq˜. The separation into hard, collinear and soft contributions elucidates the process-dependent and universal features of distributions in the edge region, represented by on-shell decay matrix elements, universal jet functions and a soft function that depends on the resonance propagator and soft Wilson lines.The work of M.B. has been supported in part by the Bundesministerium für Bildung und Forschung (BMBF) under project no. 05H15W0CAA. L.J. was partially supported by the DFG contract STU 615/1-1, and M.U. is partially supported by the STFC grant ST/L000385/1 and her research is funded by a Royal Society Dorothy Hodgkin Research Fellowship
