= La and Ce) single crystals*

RCd₃P₃ (R = La and Ce) compounds crystallize into a hexagonal ScAl₃C₃-type structure. The magnetic Ce atoms form the triangular lattice of the two dimensional layer. Thermodynamic and transport properties of RCd₃P₃ were investigated by measuring the magnetization, electrical resistivity, and specific heat. The magnetic susceptibility of CeCd₃P₃ follows the Curie-Weiss law at high temperatures with very large negative Weiss temperature. The specific heat measurement of CeCd₃P₃ clearly indicates a magnetic ordering below 0.41 K with large electronic specific heat coefficient. In this talk, anomalous physical properties due to the geometrical frustration of Ce atoms will be discussed.