U.S. business interest in the Soviet Union rose sharply Wednesday as seven companies joined forces to pursue joint ventures, another firm announced a deal and the governor of Illinois said the state might open an office in Moscow.

The developments came as Commerce Secretary William C. Verity said he is pleased with both the future prospects for trade between the superpowers and recent Soviet actions that Washington considers necessary before trade can grow.The seven-company group, to be called the American Trade Consortium, signed an agreement with the Soviet Foreign Economic Consortium in which the two parties committed themselves to establishing procedures for developing trade and economic relations between their member organizations.

The consortium is made up of units of Archer Daniels Midland Co. of Decatur, Ill.; Chevron Corp. of San Francisco; Eastman Kodak Co. of Rochester, N.Y.; Ford Motor Co. of Dearborn, Mich.; Johnson & Johnson of New Brunswick, N.J.; Mercator Corp. of New York; and RJR Nabisco of Atlanta.

Also Wednesday, Armand Hammer, chairman of Los Angeles-based Occidental Petroleum Corp., signed an agreement with the Soviets to build in the Ukraine two plastics factories worth as much as $200 million. Story, Page 7B.

Soviet Deputy Prime Minister V.M. Kamentsev said his country is ready to cooperate with the United States in large-scale projects and with small U.S. businesses in many fields, including chemistry, oil and agriculture. But he said there should be guarantees that political trends will not interrupt these trade ties.

The business officials were in Moscow to attend the 11th annual meeting of the U.S.-U.S.S.R. Trade and Economic Council. Mr. Verity and a delegation of U.S. government officials were in the capital for related meetings with their Soviet trade counterparts.

The visitor list also included Illinois Gov. James R. Thompson, who told The Journal of Commerce that his state is seriously considering opening a representative trade office in Moscow before Dec. 31. No state yet has such an office in the Soviet capital.

Gov. Thompson said he will encourage businesses in Illinois to begin the dialogue needed to bring some of our products and expertise to this country. In return, I stand ready to help open Illinois to more goods from the Soviet Union.

Much of the optimism by state and business officials reflects the new- found interest among Soviet and U.S. government leaders to talk to each other. Soviet leader Mikhail Gorbachev will host President Reagan in Moscow next month, and Mr. Verity is a long-time advocate of increased trade with the Soviets.

Mr. Verity told the more than 500 U.S. and 300 Soviets at the Trade and Economic Council meeting that both sides were trying to improve their relationship.

Past trade improvement efforts have stalled because of debates over non- commercial issues, often involving social issues. That relationship is improving, he said.

I am encouraged that there have been improvements last year in the area of human rights and emigration, he said.

Dwayne Andreas, chairman and chief executive officer of Archer Daniels as well as an executive in the trade council, said the Soviet foreign trade structure has changed radically. Officials from 20 ministries and 70 enterprises now have the right to trade directly with the West, he said.

He said the Soviet Union was encouraging cooperative enterprises and private agriculture and that a company in the Ukraine had issued stock to its most productive employees.

I see our two systems converging, not moving further apart, he said.

At the Occidental news conference, Mr. Hammer, who has had business dealings with the Soviet Union since the 1920s, said he is convinced the Soviet Union is committed to making joint ventures succeed.

Earlier this week, Honeywell Inc. announced a joint venture to supply automated production controls for Soviet fertilizer factories. Roma Food Enterprises of Piscataway, N.J., began selling pizza in Moscow from a mobile van.

Each of the seven firms already have begun talks about setting up their own ventures in the Soviet Union. Archer Daniels Midland, for example, is negotiating joint ventures in agricultural processing with the Soviet Ministry Gosagroprom.

For the others:

* Chevron is discussing possible joint venture projects involving oil exploration and development.

* Eastman Kodak expects to enter a joint venture to manufacture and market floppy disks for personal computers and blood analysis equipment used in hospitals, clinics and doctors' offices.

* Ford will continue its previously announced discussions on sale of European-designed and built Ford products in the U.S.S.R.

* Johnson & Johnson is examining the Soviet markets for consumer products, medical goods and pharmaceutical products.

* RJR Nabisco plans to become actively involved in the production of its various tobacco, cracker and biscuit products and cereals, as well as development of food manufacturing processes with the Soviets.

The Mercator Corp. is acting as merchant banker to the consortium.

The seven-company American Trade Consortium will have offices in New York and Moscow and will help the companies as they try to launch business ventures in the Soviet Union.

James H. Giffen, president of Mercator Corp., will hold that same position at the ATC.

The establishment of the ATC could not have happened without the historic improvement in relations between the two countries, Mr. Giffen said. This development has provided a major new opportunity for American business which the ATC companies would like to explore further.

The Soviet group that signed with the Americans is made up of several organizations, including the State Foreign Economic Commission, the Ministry of Foreign Economic Relations, the Bank for Foreign Economic Affairs, the Ministry of Finance, Gosplan and enterprises and production associations under several Soviet ministries.