Abstract This study linked the fermentation index of two varieties of cocoa beans: CCN 51 and ICS 6 with electrical conductivity (EC) of the water where they were immersed using a laboratory conductimeter. Mixtures of 11 fermented cocoa beans and unfermented were performed in order to obtain fermentation index from 0% (unfermented beans) to that reached by the fermented cocoa beans. Immersion times tested for determination of the electrical conductivity were 90 and 180 minutes. The results of electrical conductivity for CCN 51 and ICS 6 were 56.1 ± 12.0 to 1375.0 ± 28.0 mS/cm and 150.0 ± 19.9 to 1199.3 ± 44.5 mS/cm, respectively. Subsequent conductivity values ​​did not represent significant increases over time. The relationship between the fermentation index and electrical conductivity for CCN 51 showed positive trend, achieving a R. = 63.1%. The following function by regression: EC (CCN-51) = 1196 + 10.83 * (FI) – 0.06 *(FI). got a model with significant adjustment to be used to determine its fermentation index.