Super TV, which offered nightly movies over Channel 54 to 14,000 residents in the Baltimore and Washington areas, went off the air last night after falling victim to declining subscriptions.

Thomas C. Thompson, president of Subscription Television of Greater Washington, the company that markets Super TV, said that the company is closing up shop and will liquidate its assets over the next 60 to 90 days.

Super TV's viewers will now watch normal commercial fare on Channel 54 instead of recently released movies.

Although Thompson said the company has remained profitable up until recently, declining subscriptions have made it virtually impossible to continue.

Begun in 1981, Super TV had as many as 84,000 subscribers in 1983, but this figure has been declining steadily in the face of fierce competition from video cassettes and cable television, according to Thompson.

"It was really profitable. It was the anticipation of a sharp downturn in profitability that caused us to cease operations," Thompson said.

Subscription Television was a joint venture between the media conglomerate Field Enterprises Inc. and a company controlled by Texas businessman Clinton W. Murchison Jr.

Subscription television was seen as a transitional service offered by the television industry as cable television was phased in. Through a transmitter, a subscription television operation sends out scrambled high-frequency signals over the air to home television sets equipped with a special decoder.

For several years, Super TV was available on Washington's Channel 50 and Baltimore's Channel 54, where it alternated with normal commercial broadcasting. Viewers paid a monthly fee, plus a deposit for the decoder to unscramble the signal and watch the nightly movies and late-night adult fare shown on the station.

Earlier this year, however, Channel 50 turned to full-time commercial broadcasting, and Super TV transferred its local customers to Channel 54. Under a recent agreement with Subscription Television, Channel 54 is set to turn to such fare tonight.

Sam S. Kravetz, president of Channel 54, said that the contract to show Super TV at night was supposed to extend through 1992 but was terminated by mutual consent.

"I believe the market can stand an aggressive, independent UHF television station, which so far they have not seen," Kravetz said, explaining his reasons for terminating the contract. He said the channel has paid $1.25 million to an advertising agency for a new promotional drive, and now will show a mix of older movies and syndicated programming.

Thompson said Super TV's current subscribers have to mail in their decoders or bring them to the company's Tysons Corner headquarters to get back their initial $20 deposit.