An improved10B‐loaded liquid scintillator solution has been developed containing trimethylborate, 1‐methylnaphthalene, and 9,10‐diphenylanthracene. Cells up to 5 cm in diameter by 15.2 cm long have been prepared and tested with10B‐loadings up to 7.2% by weight (80% trimethylborate). The solution has excellent light output and pulse‐shape discrimination properties and is stable at temperatures as low as −17°C. Neutron efficiency calculations are also presented.