The charge density wave (CDW) is a collective phenomenon where electrons at the Fermi level form a density wave with an additional periodicity as compared to the atomic lattice. RE$_2$Ru$_3$Ge$_5$ (RE = Pr, Sm, Dy) crystallize in the Sc$_2$Fe$_3$Si$_5$-type structure (space group $P$4/$nmc$). They show peculiar CDW-induced lattice modulations in a certain temperature range below which those modulations disappear. Compared to Sm$_2$Ru$_3$Ge$_5$, Pr$_2$Ru$_3$Ge$_5$ has a higher transition temperature and no detailed structure refinements have been reported for the modulated phase for this compound. In this presentation, we will show that Pr$_2$Ru$_3$Ge$_5$ exhibits phase transitions at around 200 K from specific heat and transport property measurements. Satellite peaks have been observed in x-ray diffraction with a modulation wave vector q = (0.18,$\pm$0.18, 0). Unanticipatedly, satellite peaks disappear below 180 K. The modulated crystal structure of the CDW phase of Pr$_2$Ru$_3$Ge$_5$ will be presented on the basis of the superspace method.
 Bugaris, D. E et al. Charge Density Wave in the New Polymorphs of RE$_2$Ru$_3$Ge$_5$ (RE = Pr, Sm, Dy). J. Am. Chem. Soc. 2017, 139 (11), 4130-4143.