This book presents the spray pyrolysis system contains precursor chamber, spray nozzle unit, electric heater, air compressor and spray-dry controlling unit. The aim of this work is to fabricate a cost effective automatic spray-dry controlling arrangement for the spray-pyrolysis system. The micro-controller based circuit is used in this controlling arrangement.It controls spray and dry time during thin film deposition which is given through keyboard by the user. A display unit has been interfaced with controller to become helpful for the user.Finally,the thin film prepared from precursor and organic solvent of ZnO. Detailed analysis of the film formation mechanisms have been discussed in this work. An excellent performance have confirmed by using this controlling arrangement for depositing thin films by spray-pyrolysis technique. The proposed controlling system is easier to maintenance, low-cost and has no mechanical arrangement.