Message-oriented middleware (MOM) is at the core of a vast number of financial services and telco applications, and is gaining increasing traction in other industries, such as manufacturing, transportation, health-care and supply chain management. There is a strong interest in the end user and analyst communities for a standardized benchmark suite for evaluating the performance and scalability of MOM. In this paper, we present a workload characterization of the SPECjms2007 benchmark which is the world’s first industry-standard benchmark specialized for MOM. In addition to providing standard workload and metrics for MOM performance, the benchmark provides a flexible performance analysis framework that allows users to customize the workload according to their requirements. The workload characterization presented in this paper serves two purposes i) to help users understand the internal components of the SPECjms2007 workload and the way they are scaled, ii) to show how the workload can be customized to exercise and evaluate selected aspects of MOM performance. We discuss how the various features supported by the benchmark can be exploited for in-depth performance analysis of MOM infrastructures.