In this paper a discrete-continuous project scheduling problem with discounted cash flows is considered. In discrete-continuous project scheduling activities require for their processing discrete and continuous resources. Processing rate of an activity is the same function of the amount of the continuous resource allotted to this activity at a time. A positive cash flow is associated with each activity. A common payment model - payments at activity completion times is considered. The objective is the maximization of the net present value of all cash flows of the project. An application of genetic algorithm is described, and the algorithm is computationally tested. Some conclusions as well as directions for future research are given.