Abstract In this paper, we study synthesis under partial observability for logical specifications over finite traces expressed in LTLf /LDLf . This form of synthesis can be seen as a generalization of planning under partial observability in nondeterministic domains, which is known to be 2EXPTIMEcomplete. We start by showing that the usual “belief-state construction” used in planning under partial observability works also for general LTLf / LDL f synthesis, though with a jump in computational complexity from 2EXPTIME to 3EXPTIME. Then we show that the belief-state construction can be avoided in favor of a direct automata construction which exploits projection to hide unobservable propositions. This allow us to prove that the problem remains 2EXPTIME-complete. The new synthesis technique proposed is effective and readily implementable.