Doctoral thesis is dedicated to composites reinforced with knitted fabric – with polymer and cementitious matrixes. Within the framework of the thesis material samples with weft-knitted (plain) reinforcement were produced, conducted experimental tests and computer modelling using FEM in order to determine the mechanical properties of this kind of materials. In the first chapter the literature review is executed on knitted fabric usage for composites reinforcing. Existing types of knitted reinforcement were observed as well as their models and research methods. In the second chapter producing of samples and experimental research is described. The used research methods are: x-ray microtomography for evaluation structure of the real knitted fabric and tensile tests for determination of elastic properties. In the third chapter theoretical research on knitted fabric reinforced polymer matrix composites is described. Mathematical description of geometry is given and elastic properties are modelled with FEM, as well as method for the strength prediction is proposed. Chapter four is devoted to usage of knitted fabric for fibreconcrete reinforcement: the process of sample production is described and experimental results are given, as well as strength modelling. Conclusions regarding efficiency of the used methods as well as potential on usage of knitted fabric reinforced composites are drawn. The promotion paper consists of 160 pages, 8 tables, 115 figures and 4 annexes. The list of references has 192 sources.