The major objective of the Co-ordinated Research Project (CRP) on Radiotracer Technology for Engineering Unit Operation Studies and Unit Processes Optimization was the establishment of the residence time distribution (RTD) as the main universal tool for tracer investigation of industrial unit processes. RTD software for tracer data modelling and interpretation was developed and validated for problem solving purposes in major industrial processes, including fluidized beds, sugar crystallizers, trickle bed reactors, cement rotary kilns, flotation cells, grinding mills, incinerators, wastewater treatment unit and interwell communications in oil fields. Under the framework of this CRP, demonstrative and didactic experiments were undertaken to validate the RTD software and protocols