The nuclide Bh266 was produced in the Cm248(Na23,5n)Bh266 reaction at beam energies of 125.9, 130.6, and 135.3 MeV. Decay properties of Bh266 were investigated with a rotating wheel apparatus for α and spontaneous fission (SF) spectrometry under low background conditions attained by a gas-jet transport system coupled to the RIKEN gas-filled recoil ion separator. Based on genetically correlated α-α and α-SF decay chains, a total of 23 chains were assigned to Bh266 and its daughter nuclide Db262 and granddaughter Lr258. The half-life of Bh266 was measured to be T1/122=10.0-1.7+2.6s which is an order of magnitude longer than the literature data. The α-particle energies of Bh266 disperse widely in the range of Eα=8.62-9.40MeV. The maximum production cross section for the Cm248(Na23,5n)Bh266 reaction was determined to be σ=57±14 pb at 130.6 MeV, whereas the upper limit for the Cm248(Na23,4n)Bh267 reaction was σ≤14 pb at 121.2 MeV. These cross sections are discussed by comparing with the literature data as well as the theoretical calculations.