G331.5-0.1 in the Norma spiral arm is one of the most luminous and extended cores of a giant molecular cloud (GMC), containing at least six massive and dense dust condensations. Here we report the discovery, from observations of several submillimeter molecular lines that were made using the Atacama Submillimeter Telescope (ASTE) and the Atacama Pathfinder Experiment Telescope (APEX), of an unresolved, extremely high velocity molecular outflow toward the brightest and most massive dust condensation. The outflow is massive and energetic (flow mass of similar to 55M circle dot; momentum of similar to 2.4 x 10(3) M circle dot km s(-1); kinetic energy of similar to 1.4 x 10(48) ergs). These values are characteristic of flows driven by young massive stellar objects with L-bol similar to 1 x 10(5) L circle dot. We also report the detection, using the Australia Telescope Compact Array (ATCA), of a compact radio continuum source that is located at the center of the outflow and therefore likely to be its driving energy source. It has an spectral index between 4.8 and 8.6 GHz of 1.1 +/- 0: 2, suggesting that it might correspond to a collimated jet.