He previously served as Minister of Economy, Planning and Development and Technical Secretary of State to the Presidency of the Dominican Republic from 1998 to 2016.

In August 2004 he was appointed for a second time, Technical Secretary of the Presidency, under the new Government of the Dominican Liberation Party, (PLD).

[17] On August 16, 2012 the new President of the Dominican Republic Danilo Medina, confirmed him as Minister of Economy, Planning and Development of the new government.

On the morning of May 29, 2017, Temístocles Montás was arrested by the Public Ministry who accused him of being part of the corruption network of the Brazilian multinational company Odebrecht.

The arrest warrant was requested by the Attorney General of the Republic, Jean Alain Rodríguez, who accused Montas and thirteen other people of crimes of bribery, association of criminals, prevarication, illicit enrichment and money laundering.

Montás Domínguez was arrested and taken to the Ciudad Nueva Palace of Justice jail by Dominican police officers as a defendant.

On May 30, 2017, Manuel Alejandro Rodríguez and José de Jesús Bergés Martín, acting as defense attorneys for Montás, petitioned the Criminal Chamber of the First Instance Court of the National District for a writ of habeas corpus, alleging irregularities committed during the prosecution process.

On June 7, 2017, Temístocles Montás received a six-month coercion order in the Najayo model prison for his involvement in the corruption scandal of the Brazilian construction company Odebrecht.

On Saturday, July 8, the second chamber of the Supreme Court of Justice, acting as an appeal court for jurisdictional privileges, issued sentence number 2017-3043 in a public hearing, which varies the measure of coercion from Preventive prison to periodic presentation, and a bail of 15 million Dominican pesos in favor of the defense of Temistocles Montás and 6 other defendants, in her reading of the dissenting opinion, Judge Mirian Germán, presiding judge of the appeal court, argued that the evidence shown by the Public Ministry lacked of precise foundations which directly involve the accused.

[24][25] Montás was born in San Cristóbal, a province in the southern Dominican Republic, west of the capital Santo Domingo.

He is married to Mrs. Carmen Artero, with whom he has two sons and one daughter, Alfonso Temístocles, Raquel Indhira and Juan Carlos.