Investigations have been carried out about modification of multi-walled carbon nanotubes (MWCNTs) with ionic liquids (ILs) and thiophene derivatives. Morphology, as well as calorimetric, micromechanical and thermophysical properties of the investigated composites have been determined. Affirmation has been obtained that MWCNTs have been successfully functionalization, being a prerequisite for improved properties of various 1-octene content (17 and 38%) ethylene copolymer (EOC) based nanocomposites. As a result of introduction of modified MWCNTs within the polymer matrix increase of maximum temperatures of crystallization as well as crystallinity degrees of the polymer matrix occur, especially in the case of EOC 17 based systems, testifying about nucleation effect of MWCNTs. Along with rising MWCNTs content, linear increase of thermal conductivity of the system occur. It is also determined that, by rising MWCNTs content, surface hardness of the system increases. The financial support of NRP of Latvia, project IMIS2 is greatly acknowledged.