This textbook “Mathematical Foundation of Computer Science” has been designed to suit the needs of B. Tech. second year I semester and MCA first year students of JNTU, Hyderabad according to the revised syllabus. The students assigned with M. Tech., B. Sc., B.C.A. and IT related professional courses may also be benefited. Every topic has been started with necessary introduction and developed gradually up to the standard form. The theory part in each chapter has been given in a lucid explanation and number of examples has been worked out to illustrate the application of theory. Most of the worked out examples and unsolved problems in exercise have been taken from the previous examination paper of JNTU.