The papers in this special section focus on blockchain for the Industrial Internet of Things (IoT). Industrial IoT is reshaping various industrial sectors, such as manufacturing, logistics, transportation, healthcare, energy, and utilities. IIoT consists of various smart objects distributed throughout the whole industrial system to collect massive ambient data, which can be used to identify performance bottlenecks, troubleshoot faults, and detect malicious behaviors consequently enforcing effective control to the physical world. However, there are several challenges posed on IIoT before the formal adoption of IIoT across various industrial sectors. Among them, security and privacy preservation on IIoT data are the most crucial concerns. On the other hand, the blockchain technology is transforming industries by enabling anonymous and trustful transactions in decentralized and trustless environment. As a result, blockchains help to reduce system risks, mitigate financial fraud, and cut down operational cost. The convergence of IIoT and blockchains can potentially overcome the deficiencies of IIoT consequently resulting in the realization of IIoT in various industrial sectors. Both industry practitioners and academic researchers aim at realizing general, scalable and deployable blockchain-based IIoT platforms in various application domains while there are a number of challenges such as distributed consensus algorithms and data analytics with privacy-preservation in IIoT systems.