The synthesis, structure and properties of indium-intercalated compounds of molybdenum sulphoselenide, In1/3MoSxSe2-x (0 less than or equal to x less than or equal to 2) compounds were investigated. X-ray analysis shows that all these compounds possess layer-type structure with hexagonal symmetry. Studies of room-temperature magnetic susceptibility, thermoelectric power experiments and two-probe conductivity measurements in the temperature range 25-350 degrees C, confirmed that these are diamagnetic semiconductors with In1/3MoS2, In1/3MoS1.5Se0.5 and In1/3MoSxSe2-x (0 less than or equal to x less than or equal to 1.5) exhibiting n- and p-type conductivity, respectively. These results have been explained on the basis of existing band models. Thermal stability behaviour of these compounds in an air atmosphere and X-ray analysis of the oxidized product were also studied.