This paper considers the definition and evaluation of flexibility and reliability indices for short-term batch plant operation schedules. A deterministic flexibility metric (F), a stochastic flexibility metric (SF) and a stochastic reliability metric (SR) are defined in a form that is compatible with uniform discretization time MILP models. The stochastic metrics can be combined to form a single SRF index, quantifying the probability of successfully dealing with the expected uncertainty in both the operating parameters and in the availability of processing equipment. In what concerns reliability analysis, the approach exploits the task network representation of batch operation plans. Thus, the estimation of the reliability of an operation plan can be transformed into the evaluation of the reliability of an associated network, which can then be established by one of several known techniques.