She was born in Bucharest, the daughter of Sebastian Mărăcineanu and Sevastia, both 20-years old. Not much is known about her personal life, only that she had an unhappy childhood. In 1907 she enrolled at the University of Bucharest, receiving her degree in physical and chemical sciences in 1910. Her senior thesis, titled Light interference and its application to wavelength measurement, earned her a 300lei prize. After graduation, she taught at high schools in Bucharest, Ploiești, Iași, and Câmpulung. In 1915, she secured a teaching position at the Central School for Girls in Bucharest, a position she held until 1940. After World War I, with support from Constantin Kirițescu, Mărăcineanu obtained a fellowship that allowed her to travel to Paris to further her studies. In 1919 she took a course on radioactivity at the Sorbonne with Marie Curie. Afterwards, she pursued research with Curie at the Radium Institute until 1926. She received her Ph.D. from the Radium Institute; her thesis was read at the French Academy’s session of June 23, 1923 by Georges Urbain. At the Institute, Mărăcineanu researched the half-life of polonium and devised methods of measuring alpha decay. This work led her to believe that radioactive isotopes could be formed from atoms as a result of exposure to polonium's alpha rays; an observation which would lead to the Joliot-Curies' 1935 Nobel Prize. Mărăcineanu also investigated the possibility of sunlight inducing radioactivity; work which was contested by other researchers. Nevertheless, a 1927 article from the Geraldton Guardian remarked: "Cheaper radium is foreshadowed in a communication to the French Academy of Sciences by a girl scientist, Mlle. Maricaneanu, who by means of lengthy laboratory experiments, has been able to demonstrate that lead exposed for a long time to the sun recovers its radioactive properties. The mechanism of this transformation is a complete mystery but it is regarded of such tremendous importance to medical science that further close research work is to be pursued." Mărăcineanu went on to work at the Paris Observatory until 1929, after which she returned to Romania, and started teaching at the University of Bucharest. She performed experiments investigating the link between radioactivity and rainfall, and rainfall with earthquakes. On 29 November 1935, Nicolae Vasilescu-Karpen gave a lecture at the Romanian Academy of Sciences on Artificial radioactivity and Romanian works in this field, which contained clear allusions to Mărăcineanu’s research done in previous years. On 24 June 1936, she asked the Academy of Sciences to recognize the priority of her work. Her request was granted, and on 21 December 1937 she was elected corresponding member of the Romanian Academy of Sciences, Physics section. In 1937 she was named Director of Research by the Academy, and in 1941 she was promoted to Associate Professor. In 1942 Mărăcineanu was mandatorily retired. She died in 1944 of cancer, reportedly due to radiation exposure. According to some sources, she is buried at Bellu Cemetery in Bucharest, though other sources disagree on this point.
