A cellulose ether having (i) one or more substituents selected from the group consisting of methyl, hydroxyethyl and hydroxypropyl, (ii) one or more hydrophobic substituents, and (iii) one or more cationic, tertiary amino, or anionic substituents, and having a retained dynamic viscosity, %η80/25, of at least 30 percent, wherein %η80/25=[dynamic solution viscosity at 80° C./dynamic solution viscosity at 25° C.]×100, the dynamic solution viscosity at 25° C. and 80° being measured as 1% aqueous solution, is useful for modifying the viscosity of a composition selected from the group consisting of wellbore servicing fluids, cementitious formulations, ceramics, metal working fluids and cutting fluids.