After the sucessful workshop on High Energy Phenomena in Relativistic Outflows (HEPRO) held in Dublin in September 2007, a second meeting on similar topics will be held in Buenos Aires, Argentina, in October 2009. HEPRO II will be devoted to the comprehensive discussion of recent theoretical, phenomenological, and observational developments in the field of high-energy phenomena related, in one way or another, to the objects containing relativistic winds and jets. In this regard, the discussion of the recent gamma-ray observations, as well as the multi-wavelength properties of galactic and extragalactic jet sources will be covered by several review talks. We also plan to have several review talks on different aspects of the theory of gamma-ray sources, including magnetohydrodynamics, particle acceleration, and transport and radiation in relativistic outflows.

We expect that new and stimulating results and progress reports from ground-based detectors (MAGIC I/II, HESS I/II, VERITAS, CANGAROO III) and space-borne gamma-ray detectors (GLAST, AGILE, INTEGRAL, SWIFT), as well as X-ray telescopes like Chandra, XMM, and Suzaku will be presented and discussed at the meeting. As in HEPRO I, there will be presentations of recent original theoretical and phenomenological studies as invited and contributed talks. We hope to cover the basic theoretical topics of the rapidly developing field with an emphasis on the non-thermal high-energy phenomena related to all known galactic and extragalactic source populations with relativistic jets and outflows: microquasars, pulsar winds, active galactic nuclei, and gamma ray bursts. The feedback between observers and theoreticians will be an important ingredient of the meeting. We also expect some disussion about the future of the field in the light of planned instruments (CTA, AGIS, HAWC, Simbol-X, etc).

The meeting will be hosted by the Group of Relativistic Astrophysics and Radio Astronomy (GARRA) and the Instituto Argentino de Radioastronomía, under the auspices of the Argentine Astronomical Society (AAA) and the National Research Council (CONICET) of Argentina.

The talks will take place in the Main Lecture Room of the Aspen Towers Hotel, in the very centre of Buenos Aires City. It can accommodate up to 140 people. There will be a separated room for posters and another one for informal discussion (e.g. concerning future instrumentation).

A day-long excursion to the countryside is planned, including a Conference Banquet, in a "gaucho environment". Post-conference activities like visits to astronomical sites in the North West of the country, of tourism to the Patagonia, Iguazu falls, and other attractions can be organized upon request.