The idea was to gather together the reigning champions of the world's top football national leagues, in order to determine the world club champion, following the "champions cup" model of competitions such as the Latin Cup and the South American Championship of Champions, the same model that would  be used in 1955 for the creation of the UEFA Champions League.
At first, a 16-club cup was envisaged, following the FIFA World Cup intended number of participants; however, this proposal was soon shortened to an 8-club cup.
 According to Brazilian newspapers O Estado de São Paulo and Jornal do Brasil, and Spanish newspaper El Mundo Deportivo, the original 8-club plan of the Brazilian FA (organiser of Copa Rio) was to organise the competition with the reigning champion clubs of the Rio de Janeiro and São Paulo state Leagues (the first Brazilian national cup, named Taça Brasil, was not established until 1959, and the Rio de Janeiro and São Paulo state leagues were – and still are – the strongest state leagues in Brazil), as well as the reigning club champions from Uruguay, Italy, Spain, England (participants at the 1950 FIFA World Cup, held in Brazil, not to mention the status of Uruguay and Italy as former FIFA World Cup Champions and England as the founders of the sport), Portugal (the Portuguese champions were invited in order to please the huge Portuguese community living in Rio de Janeiro and São Paulo) and Scotland (based on Scotland being as successful as England in the British Home Championship).
Some other countries were briefly considered as possibilities (as Sweden, 3rd place in the 1950 FIFA World Cup whose champion Malmö FF was not invited as the club had not pleased the Brazilian football audience in a former visit to the country), but the original plan ended up consisting of a cup with the champions (1950 or 1951) of Rio de Janeiro, São Paulo, Portugal, Spain, England, Scotland, Italy and Uruguay.
According to the original plan, countries such as France and Argentina were not to be invited as they did not participate in the 1950 FIFA World Cup (Brazil's and Argentina's Football Associations had severed relations after a brawl in a 1946 match between the two national teams, resulting in the absence of Argentina from the 1950 World Cup and hence from Copa Rio 1951).
However, the French side Nice was accepted to the competition following the organizers' failure to bring a Spanish side.
Due to the failure to bring teams from Britain, the competition organizers accepted clubs from Austria (at the time, the most successful federation at the Mitropa Cup) and Yugoslavia (the next highest-ranked nation at the 1950 World Cup).
In 1952, the Brazilian Football Confederation invited teams from Argentina and West Germany, which were not invited for the 1951 edition of the tournament.

Both editions of the competition were contested between eight teams from Europe and South America, divided into two four-team groups, one in São Paulo and the other in Rio de Janeiro, at Pacaembu stadium in São Paulo and Maracanã stadium in Rio de Janeiro
The idea was to gather together the reigning champions of the world's top football national leagues, in order to determine the world club champion, following the "champions cup" model of competitions such as the Latin Cup and the South American Championship of Champions, the same model that would  be used in 1955 for the creation of the UEFA Champions League. At first, a 16-club cup was envisaged, following the FIFA World Cup intended number of participants; however, this proposal was soon shortened to an 8-club cup.  According to Brazilian newspapers O Estado de São Paulo and Jornal do Brasil, and Spanish newspaper El Mundo Deportivo, the original 8-club plan of the Brazilian FA (organiser of Copa Rio) was to organise the competition with the reigning champion clubs of the Rio de Janeiro and São Paulo state Leagues (the first Brazilian national cup, named Taça Brasil, was not established until 1959, and the Rio de Janeiro and São Paulo state leagues were – and still are – the strongest state leagues in Brazil), as well as the reigning club champions from Uruguay, Italy, Spain, England (participants at the 1950 FIFA World Cup, held in Brazil, not to mention the status of Uruguay and Italy as former FIFA World Cup Champions and England as the founders of the sport), Portugal (the Portuguese champions were invited in order to please the huge Portuguese community living in Rio de Janeiro and São Paulo) and Scotland (based on Scotland being as successful as England in the British Home Championship). Some other countries were briefly considered as possibilities (as Sweden, 3rd place in the 1950 FIFA World Cup whose champion Malmö FF was not invited as the club had not pleased the Brazilian football audience in a former visit to the country), but the original plan ended up consisting of a cup with the champions (1950 or 1951) of Rio de Janeiro, São Paulo, Portugal, Spain, England, Scotland, Italy and Uruguay. According to the original plan, countries such as France and Argentina were not to be invited as they did not participate in the 1950 FIFA World Cup (Brazil's and Argentina's Football Associations had severed relations after a brawl in a 1946 match between the two national teams, resulting in the absence of Argentina from the 1950 World Cup and hence from Copa Rio 1951). However, the French side Nice was accepted to the competition following the organizers' failure to bring a Spanish side. Due to the failure to bring teams from Britain, the competition organizers accepted clubs from Austria (at the time, the most successful federation at the Mitropa Cup) and Yugoslavia (the next highest-ranked nation at the 1950 World Cup). In 1952, the Brazilian Football Confederation invited teams from Argentina and West Germany, which were not invited for the 1951 edition of the tournament.
Both editions of the competition were contested between eight teams from Europe and South America, divided into two four-team groups, one in São Paulo and the other in Rio de Janeiro, at Pacaembu stadium in São Paulo and Maracanã stadium in Rio de Janeiro
Copa Rio (international tournament)