Marinov was born on 1 February 1931 in Sofia to a family of intellectual communists.^[4] In 1948 he finished Soviet College in Prague, then studied physics at the Czech Technical University in Prague and Sofia University. He was an Assistant Professor of Physics from 1960 to 1974 at Sofia University. In 1966–67, 1974, and 1977 he was subject to compulsory psychiatric treatment in Sofia because of his political dissent. In September 1977 Marinov received a passport and he successfully emigrated out of the country, moving to Brussels. In 1978, Marinov moved to Washington, D.C. Later he lived in Italy and Austria. In his later years, Marinov earned a living as a groom for horses.

On 15 July 1997, Marinov jumped to his death from a staircase at a library at the University of Graz, after leaving suicide notes.^[3] He was 66 years old and was survived by his son Marin Marinov, who at the time was a vice-Minister of Industry of Bulgaria.

One of Marinov's interests was the quest for free energy sources via construction of toy theories (new axiomatic systems that putatively describe our physical reality) and their experimental testing against mainstream physical theories. In 1992 Marinov wrote a letter to German Federal Chancellor Helmut Kohl in support of a German company, Becocraft, that was doing research into "free energy" technologies and had recently been the target of lawsuits. In the letter, Marinov threatened to set himself on fire at the steps of the German parliament if Kohl was not willing to intervene in favour of Marinov's associates.

Marinov attempted to find experimental disproof of the theory of relativity by testing the speed of light in different directions using an arrangement of coupled mirrors and coupled shutters.^[5][6] Marinov reported in 1974 that he had measured an anisotropy of the velocity of light.^[7] However, Marinov's claims have not found acceptance within the scientific community, despite his energetic efforts to promote his claims. Marinov planned to develop an updating of the relativistic mechanics and electrodynamics, as described in his self-published book Eppur si Muove.^[4] Marinov succeeded in having his claims presented in numerous publications including peer-reviewed journals.^{[8][9][10][11][12][13][14][15][16][17][18][19][20][21]}

Marinov was involved publicly with many quarrels with John Maddox, the editor of Nature, who refused to print either his papers or his letters to the editor. He retaliated by securing the funds to place a full-page advertisement in Nature expressing his frustration with what he regarded as the dogmatic attitude of the establishment.^[22] Marinov himself published a journal, Deutsche Physik, of which he was editor-in-chief and which discussed mainly his ideas on physics.

Stefan Marinov was interested in experiments alleged to violate known physical laws.^[23][24] Marinov claimed to have seen in operation and learned the secret of the so-called "Swiss ML converter" or Testatika electrical generator, another alleged perpetual motion machine, at a religious commune in Switzerland called Methernitha.^[3] According to Marinov's account, this 500-member commune, led by religious leader Paul Baumann, met all its energy needs using this device.^[3]

Marinov has been editor of a five-volume encyclopaedic series called "Classical Physics".^{[25][26][27][28][29]} In 1993 Marinov also authored a book on electromagnetism^[30] which discoursed on his belief that mainstream scientific thought was mired in dogma and had discarded still-valid knowledge from scientific thought of previous eras. In 1997 in the last issue 21 of Deutsche Physik, Marinov self-published experimental results that disprove that the Siberian Coliu, constructed by Marinov himself, is a perpetual motion machine, and where Marinov concluded that Ampere's law in electromagnetism is correct.^[1][2] Most of Marinov's friends think these negative results on constructing a source of free energy (in order to solve the global energy needs of humanity) might have pushed him to commit a suicide.^[3][31]