The task of a priori valuation of information system investments has attracted a lot of research for a long time. One of the main themes of this research has been which types of consequences information system investments result in and how these consequences can be incorporated in the a priori valuation of that investment. Much of this research has stated the problem as how to incorporate intangible consequences in the valuation since intangible costs and benefits are assumed to represent a large part of the consequences from an information system investment. These consequences are therefore highly relevant in the appraisal of information system investments. This paper is concerned with the question of how intangible consequences can be incorporated in the a priori valuation of information system investments. To answer this question, the paper presents a theoretical model for the valuation of information system investments based upon a continuous time discounted cash flow model, The general model argued for in this paper is that usage results in consequences which must be into cash flows to be incorporated in a discounted cash flow model. Usage is chosen as the underlying value creating function since it is the basic underlying function that creates all consequences specific to the information system investment. Some of these consequences can be measured and valued and thus expressed in cash flows and do therefore not cause any valuation problems. Intangible consequences on the other hand cannot be measured or valued when they occur. If these consequences never affect the cash flow they do not pose a valuation problem. It is more likely however that they will affect the cash flow but at a later time. This paper develops a stochastic cash flow model to incorporate the uncertainty and characteristics of when the intangible consequences affect the cash flow by using a Brownian motion in the valuation model. The expectations of the future cash flows are transformed into risk-neutral expectations so a risk-free rate of return can be used as a discount factor.