The distributed nature of the reflection process is considered for pump‐and‐probe‐type picosecond transient thermoreflectance (PTTR) measurements. A first‐order approximation is given for the temporal dependence of the reflectivity for temperature distributions created by picosecond laser pulses. It was found that PTTR flashes back the temperature profile created by the pump pulse. The problem of determining the thermal transport properties from PTTR measurements is discussed.