We report the superconductivity in the single crystal of Sr2.5Ca11.5Cu
24O41 at T-c(onset) = 6.5 K under an optimal pressure of about 4.5 GPa
. Normal resistivity along ladder direction rho(c), gradually changes
from T-linear to T-2-dependence with increasing an applied pressure. T
he normal resistivity ratio rho(alpha)/rho(c) in the ladder plane indi
cates the crossover from 1D to 2D with increasing an applied pressure.