17Despite a body of research carried out on thermally coupled processes in soils, understanding 18 of thermo-osmosis phenomena in clays and its effects on hydro-mechanical behaviour is 19 incomplete. This paper presents an investigation on the effects of thermo-osmosis on 20 hydraulic behaviour of saturated clays. A theoretical formulation for hydraulic behaviour is 21 developed incorporating an explicit description of thermo-osmosis effects on coupled hydro-22 mechanical behaviour. The extended formulation is implemented within a coupled numerical 23 model for thermal, hydraulic, chemical and mechanical behaviour of soils. The model is 24 tested and applied to simulate a soil heating experiment. It is shown that the inclusion of 25 thermo-osmosis in the coupled thermo-hydraulic simulation of the case study provides a 26 2 better agreement with the experimental data compared with the case where only thermal 27 expansion of the soil constituents was considered. A series of numerical simulations are also 28 presented studying the pore water pressure development in saturated clay induced by a 29 heating source. It is shown that pore water pressure evolution can be considerably affected by 30 thermo-osmosis. Under the conditions of the problem considered, it was found that thermo-31 osmosis changed the pore water pressure regime in the vicinity of the heater in the case where 32 value of thermo-osmotic conductivity was larger than 10 -12 m 2 .K -1 .s -1 . New insights into the 33 hydraulic response of the ground and the pore pressure evolution due to thermo-osmosis are 34 provided in this paper.