We discuss general properties of moduli stablization in KKLT scenarios in type IIB orientifold compactifications X 6 . In particular, we find conditions for the Kähler potential to allow a KKLT scenario for a manifold X 6 without complex structure moduli, i.e. h (−) (2,1) (X 6 ) = 0. This way, a whole class of type IIB orientifolds with h (−) (2,1) (X 6 ) = 0 is ruled out. This excludes in particular all Z N -and Z N × Z M -orientifolds X 6 with h (2,1) (X 6 ) = 0 for a KKLT scenario. This concerns Z 3 , Z 7 , Z 3 × Z 3 , Z 4 × Z 4 , Z 6 × Z 6 and Z 2 × Z 6 ′ -both at the orbifold point and away from it. Furthermore, we propose a mechanism to stabilize the Kaehler moduli accociated to the odd cohomology H (1,1) − (X 6 ). In the second part of this work we discuss the moduli stabilization of resolved type IIB Z N -or Z N × Z M -orbifold/orientifold compactifications. As examples for the resolved Z 6 and Z 2 × Z 4 orbifolds we fix all moduli through a combination of fluxes and racetrack superpotential.