The present paper analyzes historical features and linguistic evidences on Dutch documents dating from the beginning of the 18th century about the Portuguese language in Timor. These documents are located at the Arsip Nasional (ANRI ‘National Archive’) in Jakarta, Indonesia, and at the Koninklijk Instituut voor Taal-, Land- en Volkenkunde (KITLV ‘Royal Netherlands Institute of Southeast Asian and Caribbean Studies’) in Leiden, Netherlands. The choice to analyze the Dutch documents was not random due to the fact that these documents are understudied until now. By its turn, the Portuguese documentation about Timor is well studied by Portuguese historians and philologists since the 19th century. The documents located in Indonesia date from the 18th century and are the main source of this study, while the documents from Netherlands date from the 17th century and were only used to confirm the present analysis as additional evidences. Thus, in (2), the main features of Portuguese spoken in Timor-Leste will be pointed out. In (3), the corpus will be analyzed searching for historical information and linguistic evidences which may contribute to a better knowledge on the origin, formation and development of the Portuguese variety spoken in Timor-Leste. Finally, in (4), there are the final remarks about the analysis done on the paper.