The article outlines models of system functioning and methods to use these models for solving problems of optimal information operations use for systems functioning. Models provide means for estimation of information operation effects and as a result, the operational properties of systems and their functioning with regard to information operations fulfilled. Such systems' functioning is changed due to information operations. Examples of operational properties are efficiency, the effectiveness of system functioning, system capabilities and system potential. Operational properties are estimated based on functioning effects. Such effects of information operations are manifested through a system functioning under the conditions of a changing environment. An estimation of effects and operational properties is fulfilled analytically. This makes it possible to solve appropriate practical problems of optimal information operations usage as mathematical problems. It is made through plotting the dependences of the predicted values of effects and operational properties of information operations and corresponding IT usage against the variables and options of problems solved. To develop this type of model, the use of information operations during system functioning is analyzed through an example of a technological system. An exemplary modeling of the effects of technological information and the related technological noninformation operations of technological systems operation is provided. Based on concept models of information operations of technological systems, functioning set-theoretical models followed by functional models are introduced. An example of operational properties indicators estimation is considered. It is based on Architecture of Integrated Information Systems (ARIS) diagramming tools' usage. Use cases of such indicators include choosing optimal information operations characteristics.