This paper presents a symmetric key block cipher technique using Cellular Automata (CA). The proposed system deals with theory and application of cellular automaton. Cellular automata have the property of state transition that is basis to define fundamental transformations for encryption and decryption in the enciphering system. Firstly, the patterns are generated using MATLAB (v2011) and then the cryptographic system is implemented in C language but it can be implemented in other languages too. Different rule configurations of CA are used to form hybrid reversible cellular automata to be used in encryption and decryption of the data in the form of string or character array.