Treasury Secretary James A. Baker III will be the guest of honor at a reception Monday night, only hours before a two-day bipartisan congressional summit begins on international monetary reform amid signs that the Treasury may lend additional support to the unusual meeting.

A Treasury spokeswoman said yesterday that "we see nothing wrong with the Hill putting on a monetary conference, and we have no objections." She added that, in addition to Baker's appearance at the reception, "it is possible that the Treasury might participate" in the conference.

The congressional conference was called by Rep. Jack Kemp (R-N.Y.) and Sen. Bill Bradley (D-N.J.) to discuss changes in the exchange rate system that might provide an alternative to rising protectionist sentiment and how they affect trade.

Bradley and Kemp expect the conference to generate a congressional commission that would be expected to publish a report on monetary reform in time for its consideration by the heads-of-government economic summit scheduled for Tokyo next May.

Baker had made clear earlier that it would be premature for the executive branch to endorse a formal monetary conference before the International Monetary Fund had concluded that such a step is necessary. This will be on the agenda for the IMF Interim Committee next spring.

But Baker appears to have no objections to serious congressional consideration of the exchange rate issue. He will greet about 100 government and private individuals from the United States and abroad at the Federal Reserve headquarters here. The participants will spend the following two days discussing international economic issues at the National Academy of Sciences.

Among the key questions to be debated are reform of the monetary system, protectionism, the possibility of achieving a political consensus for more stable exchange rates and a forum topic listed as: "The G-5 Accord -- The First Fifty Days/ Where do We Go in 1986?"

Baker's initiative led to a meeting of the G-5, or Group of Five, finance ministers, in New York on Sept. 22 that resulted in coordinated intervention to bring down the value of the dollar. Since that time, it has declined about 10 percent.

Coincidentally, it was learned that the G-5 deputies will meet in Paris on Nov. 14, immediately following the Kemp-Bradley session. The United States will be represented by Assistant Treasury Secretary David Mulford.

Participants in the congressional monetary summit on Nov. 12 and 13 will include Mulford, Deputy Treasury Secretary Richard Darman, U.S. Trade Representative Clayton Yeutter, Federal Reserve Board Vice Chairman Preston Martin, Fed Governor Martha Seger and Governor-designate Manuel Johnson, who currently is an assistant secretary of the Treasury.

Other participants include a wide cross section of banking, financial and academic trade and monetary experts from here and abroad. Major addresses will be delivered by Jacques Attali, chief counselor to French President Francois Mitterrand; by former French president Valery Giscard d'Estaing; and by Robert Muldoon, former prime minister of New Zealand.

Congressional interest in international monetary reform has blossomed during the past year, with growing realization that distortions in exchange-rate relationships may be at the root of the American global trade deficit, which reached $123 billion last year and may touch $150 billion this year.

Until recently, the conventional wisdom followed by the Reagan administration was that little could be done to change the international monetary system in a way that would bring beneficial trade effects. European nations, led by France, have called for some sort of international monetary conference to discuss the possibilities. But the United States rejected this notion, as well as the regular use of intervention as a tool to affect exchange rate relationships.

The summit was the brainchild of two former congressional staffers, David Smick, who was an administrative assistant to Kemp, and Richard Medley, who formerly worked for the House Banking Committee. A Smick-Medley political consulting firm is now advising Kemp and Bradley on the conference.