Trust evaluation in decentralized M2M communities, where several end-users provide or consume independently M2M application services, enable the identification of trustless nodes and increase the security level of the community. Several trust management systems using different trust evaluation techniques are presented in the application field of M2M. However, most of them do not provide a secure way to store the computed trust values in the community. Moreover, the trust agents participating in the trust evaluation process are not securely identified and could lead to misbehavior among the trust agents resulting in non-reliable trust values. This research identifies several problems regarding decentralized M2M application services and the trust evaluation process. In order to overcome these issues this research proposes a novel approach by integrating blockchain technology in trust evaluation processes. Moreover, this publication presents a concept for using blockchain within the system for decentralized M2M application service provision. Finally, the combination of P2P overlay and blockchain network is introduced in order to verify the integrity of data.