  We have found that CeCd$_{3}$P$_{3}$ crystallizes into a hexagonal
ScAl$_{3}$C$_{3}$-type structure. The optical, transport and magnetic
properties of CeCd$_{3}$P$_{3}$ were investigated by measuring the diffuse
reflectance, electrical resistivity and magnetization. CeCd$_{3}$P$_{3}$ is a
semiconductor with the fundamental band gap of approximately 0.75 eV. The 4$f$
electrons of Ce$^{3+}$ ions are well localized but do not show long range order
down to 0.48 K, presumably due to the geometrical frustration of Ce atoms. The
magnetic ordering temperature is possibly lower than that of isostructural
CeZn$_{3}$P$_{3}$ (0.75 K). Because several $f$-electron compounds with the
ScAl$_{3}$C$_{3}$-type structure are quantum spin systems, CeCd$_{3}$P$_{3}$
may be a candidate of quantum spin liquid. On the other hand, the relatively
large band gap compared to approximately 0.4 eV in CeZn$_{3}$P$_{3}$, would not
be intimate with the observation of photoinduced Kondo effect, providing a
potentially new range of applications of devices based on the Kondo effect.
