Summary: During the last two decades power systems industry has undergone many changes world-wide, seeking to create competitive wholesale electricity markets. In these markets, power suppliers and consumers are free to negotiate the terms of their contracts, e.g., energy prices, power quantities and contract durations in several auctions structures. Multi-agent systems are a widely used computer paradigm in the simulation of these new power market business models. A usual approach is to develop a specific application within a standard agent management framework, such as JADE. Several approaches are commonly used for market simulations: those that evaluate the behavior of supplier and demand agents under several auction models, and others that focus on each market’s particular operations and problems, i.e., they simulate realtime market operating conditions. This work presents a multi-agent-based simulator for Brazilian electrical power market, incorporating operational and commercial models.