The RuSr2GdCu2O8 (Ru1212) crystal with the highest superconducting transition temperature Tc(end)=54.0 K (Tc(onset)=65.0 K) has been obtained from the nominal composition of Ru:Sr:Gd:Cu=0.9:2.0:1.0:2.1. The prepared compounds are not in a single Ru1212 phase and contain a small amount of Sr2GdRuO6 and SrRuO3 impurity phases. Possible correlation between the high-Tc phase and the impurity phase is discussed.