We report the synthesis of a new series of layered hydroxides based on rare-earth elements with a composition of RE(OH)2.5Cl0.5⋅0.8 H2O (RE: Eu, Tb, etc.) through the homogeneous precipitation of RECl3⋅x H2O with hexamethylenetetramine (HMT). Rietveld analysis combined with direct methods revealed an orthorhombic layered structure comprising a positively charged layer of [RE(OH)2.5(H2O)0.8]0.5+ and interlayer Cl− ions. The Cl− ions were readily exchangeable for various anions (NO3−, SO42−, dodecylsulfonate, etc.) at ambient temperature. Photoluminescence studies showed that the compounds display typical RE3+ emission. With rare-earth-based host layers and tunable interlayer guests, the new compounds may be of interest for optoelectronic, magnetic, catalytic, and biomedical materials.