Actually the Galibi-Marworno population uses as its maternal language a variation of the creole spoken in French Guiana. This dialect is used as a língua franca by the indigenous peoples of the Lower Oiapoque, who recognize phonetic differences between the dialect spoken by the Karipuna and the dialect spoken by the Galibi-Marworno. This “indigenous” creole is distinct from the “Black” creole of French Guiana both in terms of its phonetic and lexical aspects which still have not been sufficiently studied. The creole dialect came to predominate among the Galibi-Marworno to the detriment of the various languages spoken by their ancestors. Nimuendaju, who was on the Uaçá River in 1925, recorded more than 100 words in the Galibi language, a dozen in the Aruã language and only two words in Maraon.

French creole has remained the maternal language despite the efforts of the SPI to prevent its use, since it implied Galibi-Marworno use of French habits, which was not looked upon favorably by the Brazilian state in a boundary area which was only definitively annexed to Brazilian territory in 1900. The school built in the Uaçá region in 1934 prohibited the use of creole by the students, reinforcing this prohibition with the use of the palm-slapper (an instrument of punishment).

The study of this variant of French creole began in the 1980s, among the Karipuna and Galibi-Marworno, by Francisca Picanço Montejo, linguist of the Indigenist Missionary Council, who had technical assistance from the linguists Ruth Montserrat (UFRJ) and Márcio Silva (then at UNICAMP). An orthography of Karipuna and Galibi-Marworno was produced and its grammar systematized. According to this orthography, the dialect is designated by the word "kheuol". The language is being studied by other researchers among the Karipuna.