Two types of radiation emission have been detected during the on state of threshold switching events in noncrystalline chalcogenide thin films having a transparent SnO2(NESA) bottom electrode and a heat conducting top electrode. The common form of the radiation is an emission at about 1.2–1.4 &mgr;m which (i) is propagated through a wide solid angle, (ii) is relatively independent of time during the on‐state pulse (iii) has an integrated intensity which is approximately a linear function of on‐state power and a superlinear function of on‐state current, and (iv) requires a minimum on‐state current for initiation. The second type of emission is between 0.75 and 3 &mgr;m and is detected rather rarely. This latter emission has a characteristic intensity which is a steeply peaked function of on‐state time and appears to be possibly highly collimated. The peaked emission has been detected in pulsed modes using single set pulses and has also been detected continuously using low‐frequency repetitive threshold set pulses. Both radiation effects appear to be nonthermal in origin.