Clock skew scheduling is a technique that intentionally introduces skews to memory elements to improve the performance of a sequential circuit. It was shown in (Ravindran, 2003) that the full optimization potential of clock skew scheduling can be reliably implemented using a few skew domains. In this paper we present an optimal skew scheduling algorithm for sequential circuits with flip-flops. Given a finite set of prescribed skew domains, the algorithm finds a domain assignment for each flip-flop such that the clock period is minimized with possible delay padding. Experimental results validate the efficiency of our algorithm and show 17% improvement on average in clock period.