GSM Modem Based Data Acquisition is a process control system. It helps in collecting data from various processes present at distant places. It helps one to monitor parameters like temperature, rainfall, humidity etc. the Service personnel need not to visit distant sites for data collection .the data is collected automatically formed a data base and stored in a PC. It can be used in industries as well as in home automation. This system uses AVR microcontroller ATmega 644P. The inbuilt ADC receives analog data from sensors and converts it to digital data and passes it to the microcontroller. The sensors continuously send data from the distant site. This system is interfaced with a GSM modem.