K0.3MoO3 single crystals with the size of 2cm×1.5cm×1cm have been grown by electrolytic reduction of K2CO3-MoO3 melt with a K2CO3-to-MoO3 mole ratio of 1 to 4.32. The temperature dependence of normalized resistivity R(T)/R(290K)-T of a K0.3MoO3 single crystal has been determined. It is found that the semiconductor gap of the single crystal is 1320K(0.11eV). The threshold electric field ET is ０.1２９Ｖ／ｃｍ derived from the data of nonlinear conductivity at T=77K．ＤＳＣ study of the samples shows that the K0.3MoO3 single crystal undertakes a new Peierls phase transition around 240K and that the phase transition is of first order. The Δｃp-Ｔ curve shows that the phase transition around T=180K is a combination of a second order and a first.