Photo courtesy of the MCCA

The maximum buildout of the Hynes Convention Center property is coming into sharper focus as the marketing process proceeds and the state legislature debates whether to authorize its sale.

The 5.8-acre site on Boylston Street could accommodate between 2 and 3 million square feet of redeveloped commercial space, said Frank Petz, managing director of investment sales at Colliers International in Boston. The Massachusetts Convention Center Authority selected Colliers in December to market the property.

The site appears best-suited for a mixed-use project, Petz said.

“At that sort of density levels, it’s got to be mixed-use, and the neighborhood is going to clamor for mixed use as well,” he said. “That whole area is in demand across all property types: hotel, retail, office and residential.”

The Hynes site include two parcels. According to Boston Planning & Development Agency spokeswoman Bonnie McGilpin, each parcel is located in two separate zoning districts which have a maximum floor area ratio of 8 and 10 and building height limits of 120 and 155 feet, respectively.

Colliers has assigned a dozen employees to conduct community outreach and research the potential development capacity of the site, including construction costs and engineering questions because part of the site is located on a deck above the Massachusetts Turnpike. The property will be offered on a fee simple basis, as opposed to a long-term lease, Petz said.

“It is one of the most prime development sites in the country in terms of infill development of this scale, and everyone is calling to try to get ahead as they race for information,” he said. “We’re not delivering information until we have facts.”

At a State House hearing in January, Back Bay business owners asked legislators to “decouple” the proposed sale from a $500 million expansion of the Boston Convention and Exhibition Center in South Boston. Proceeds from the Hynes sale would help pay for the BCEC project under the pending legislation.

MCCA officials say the Hynes building is obsolete and requires $200 million in repairs and maintenance.

But Back Bay neighborhood and business groups said the proposed sale is moving forward without an analysis of the economic impact on Back Bay. Local hotels and restaurants say their business relies heavily on trade shows at the Hynes, which attracts an estimated 500,000 annual visitors.

If the legislature authorizes the MCCA to proceed with a sale, the development plans will be subject to BPDA review.

“We’re out there to find the right buyer who has a feasible business plan, is capable of executing on that business plan, and pays the right price,” Petz said.