This study examines the behavior of the firm which faces uncertainty in demand but can adjust its output once the uncertainty is resolved, using contingentclaims analysis. The paper finds that (i) the optimal output of the firm with ex post adjustment capability is less than that of the firm without production flexibility; (ii) the optimal ex ante output increases with the higher interest rate; (iii) the greater the marginal cost associated with the expost adjustment and/or salvage value, the greater the optimal ex ante output; and (iv) the effect of demand volatility and production lead time on the optimal ex ante output could be either positive or negative. Based upon the study's findings, some important managerial decision implications are discussed.