Biomass tends to form deposits and tends to slag during combustion. This study focused on deposits obtained from a circulating fluidized bed (CFB) in a biomass power plant. Analyses using scanning electron microscopy, energy-dispersive spectrometry, and X-ray diffraction are also included. The results indicate that the deposits are dense with a certain hardness, which resulted from the erosion of particles in the CFB. The deposits are high in K, Na, Cl, and Ca, whereas Si, Al, Mg, and S contents are relatively lower. KCl and K2SO4 are the main components of the deposits. The particles in the flue are captured by the viscous layer that was formed by the condensation of gaseous KCl and K2Ca(SO4)(2) on the surface of the tubes. Moreover, deposits are formed under the effect of the adhesion and capturing processes, in alternation.