Construc ting composite services by using of services offered by third parties is an attractive and inexpensive way for service brokers and aggregators to enhance differentiation from their competitors. When multiple services provide the same or similar functionalities, selecting those that satisfy users' non­ functional requirements is crucial. In many cases, non-functional properties of services are heavily dependent on the activity of the network delivering those services whilst the network activity follows certain time-sensitive rules. We present a service selection algorithm that takes into account time-sensitive variations of non-functional propensities of services to identify a service combination offering the highest quality within a specified time interval.