This review summarizes the development, investigation, and optimization of polymorphic lithium cobalt phosphate LiCoPO₄. One of the three polymorphs known to date, olivine-type or Pnma-LiCoPO₄, shows intriguing electrochemical properties as a high-voltage cathode material, which are of interest for next-generation lithium-ion batteries with higher energy density. Hence, scientists have developed optimization strategies to improve its performance for commercial applications. Herein, a number of procedures for the synthesis of Pnma-LiCoPO₄ is presented, including thermodynamic as well as kinetically controlled approaches. The continuous improvement of its electrochemical performance is illustrated, which was realized by the development of solvothermal techniques that allow a precise particle size and morphology control. In the course of these investigations, two new polymorphs, Pna2₁-LiCoPO₄ and Cmcm-LiCoPO₄, have been discovered which show different physical and structural properties compared to Pnma-LiCoPO₄. Despite their significantly poorer electrochemical performance, these polymorphs allow interesting insights into the variable structure chemistry of transition-metal phosphates, which canalizes in intriguing magnetic and thermal properties. The similarities and differences in the chemical and physical properties of Pnma-LiCoPO₄, Pna2₁-LiCoPO₄, and Cmcm-LiCoPO₄ are discussed.