Viscous Demand (Research Seminar, October 4th, 2001) Roy Radner Leonard N. Stern School Professor of Business, New York University Abstract: In many markets, demand adjusts slowly to changes in prices, i.e., demand is "viscous." For such a market, the time path of a firm's prices acquires added significance, compared with the case of instantaneous demand response. In this paper I explore some problems in strategic dynamic pricing of a service, in the presence of viscous demand, for simple models of a monopoly and a duopoly.