Orthorhombic and hexagonal CeOHCO3 crystals were grown by a hydrothermal method. X-ray diffraction, scanning electron microscopy and optical spectroscopy were used to characterize the samples. The orthorhombic phase was formed prior to the hexagonal phase following an increase in temperature. The two phases correspond to different morphologies and luminescent performance. Orthorhombic CeOHCO3 crystals are shuttle-like while hexagonal CeOHCO3 is butterfly-like, and the former displays a much stronger luminescence than the latter,