Quantum key distribution is built upon the basic principles of quantum mechanics and as a consequence all of these protocols relies on quantum properties, like superposition and entanglement, to distribute the key between communicating parties and these quantum properties are also used to detect unauthorized interception of keys. This paper presents a Prepare and Measure quantum key distribution protocol that amplifies the detection ability of the eavesdropper in between the sender and receiver by the use of a decoy state. In the proposed work, only Alice announces her bases which is unique in domain of Prepare and Measure protocol. This work also achieves bit mismatch up to 50% while eavesdropper is present in the quantum communication channel.