Relationship between technology and organisational changes in public sector has become the subject of increasingly intensive research within the last decade. Studies dealing such relationship could be divided in two major groups - first group regards ICT in the e-government period as the key factor of organizational transformation and the second group regards ICT as an equal and co-dependent element in relation to other organizational factors. These two groups of studies could be further classified within two organizational theories - Technological Determinism and Socio-Technical Theory. The aim of this paper is to critically analyse those theories in the sense of formal theoretical framework to explain relationship between ICT and other organisational factors through the lens of Leavitt’s diamond. On the basis of critical analysis and synthesis of available literature the draft of a new conceptual model for explaining such relationship will be proposed.