The Caribbean being part of the Lesser Antilles volcanic arc such as Guadeloupe, Martinique, Dominique, Montserrat, Saint Lucia, etc., must face the fragility of their energetic system and environment, given their insularity. However, these territories, which are home to young volcanic systems, possess a huge potential for power generation from High-Temperature (HT) geothermal energy. This energy is continuously available and economically competitive. However, so far, it remains difficult to develop in these islands. Indeed, even though the first exploration works have been carried out in the 1970s in some of these territories, the HT (260°C) Bouillante geothermal power plant in Guadeloupe, exploited since 1986, is currently the unique example of electricity production (15 MWe and about 6% of the annual electricity needs of the Island) in the Caribbean area. The main objectives of this study are to present, for the first time, the main geochemical characteristics of the deep fluids from the geothermal wells and some thermal springs existing in Guadeloupe, Martinique, Dominica, Montserrat and Saint Lucia. New auxiliary chemical thermometric relationships such as Na-Li, Na-Rb, Na-Cs, K-Sr, K-Fe, K-Mn, K-F and K-W, and Li isotopes, were also tested on these deep fluids, which can be useful for future works of geothermal exploration in these islands. In order to reach these objectives, this paper has exploited two types of geochemical data: 1) data obtained after an extensive literature review and 2) data acquired in Guadeloupe (with new analyses on old stored fluid samples) and Martinique (with a campaign of fluid sampling carried out in 2022), during this study. If in the past, some deep wells drilled in the Saint Lucia and Martinique islands had to be abandoned and closed, the results of this study integrating new exploration works and deep wells recently drilled in Dominica and Montserrat suggest promising geothermal developments in the Caribbean area.