Novel KCaR(BO3)2 (R = La, Pr and Nd) compounds have been obtained by solid-state synthesis. Specifically, single crystals of KCaNd(BO3)2 and KCaPr(BO3)2 were grown by using a top seeded solution growth method from the KBO2 flux. These crystal compounds belong to the orthorhombic system, Pbca space group. KCaLa(BO3)2 exhibits high transparency in the range of 200–900 nm. Pr and Nd compounds have a strong emission bands that are related to the well-known electron transition of Pr3+ (3P0 → 3H6 at 630 nm, 3P0 → 3F2 at 670 nm) and Nd3+ (4F3/2 → 4I9/2 at 875 nm, 4F3/2 → 4I11/2 at 1054 nm).