Blockchain, the underlying technology behind Bitcoin, emphasises on decentralizing services and verifiability. It makes use of a distributed peer-to-peer network in which nodes collectively affirm the provenance of transactions. The peers in the Blockchain network uses a consensus mechanism to affirm transactions. In a Blockchain network that uses Proof-of-Work (POW) as a consensus mechanism, the time required to confirm transactions are much higher and thereby it affects the scalability. This necessitates an approach to enhance the performance of POW. This paper, proposes to use threads to calculate merkle root and to perform POW in solo and in parallel by multiple miners. With parallel merkle root calculation method, the nodes in each level of the merkle tree is equally distributed to n-threads where they calculate the hash of the adjacent pairs of nodes and return the result. This process is repeated until the merkle root is found. Similarly, threads are used in both solo mining with threads and parallel mining by multiple miners with threads, where each thread solve the cryptographic hash puzzle using the allocated nonce range, thereby reducing the time that is taken to solve the block. The test results shows that there is a substantial enhancement in the performance. © 2020, Institute of Advanced Scientific Research, Inc.. All rights reserved.