Abstract. We study the complexity of computing Kronecker coefficients g(λ, µ, ν). We give explicit bounds in terms of the number of parts ℓ in the partitions, their largest part size N and the smallest second part M of the three partitions. When M = O(1), i.e. one of the partitions is hook-like, the bounds are linear in log N , but depend exponentially on ℓ. Moreover, similar bounds hold even when M = e O(ℓ) . By a separate argument, we show that the positivity of Kronecker coefficients can be decided in O(log N ) time for a bounded number ℓ of parts and without restriction on M . Related problems of computing Kronecker coefficients when one partition is a hook, and computing characters of Sn are also considered.