The fat bloom is a recrystallization process, resulting in the surface of the chocolate becoming opaque and white. The objective of the research was to determine the kinetics of appearance of the referred phenomenon by evaluating the whiteness index (WI) in Peruvian chocolate for sale with 45 and 70% of cocoa. The kinetics were determined for the accelerated method of temperature cycles with cycles of 30 ± 1°C (for 8 hours) and 20 ± 1°C (for 16 hours) at relative humidity of 30; 50 and 70 percent; the measurements were inter-daily. The relative humidity did not significantly influence (P > 0.05) in the fat bloom kinetic before 48 hours of storage. The highest average (IB) observed was 55.7 ± 0.25, reached by chocolate at 70% cocoa, stored at 30% of humidity. The kinetic of fat bloom is given by the inverted exponential function: WI = WIf - (WIf - WIi) e-Kθ