The purpose of the present paper is to pursue further study of a class of linear bounded operators, known as n-quasi-m-isometric operators acting on an infinite complex separable Hilbert space H. We give an equivalent condition for any T to be n-quasi-m-isometric operator. Using this result we prove that any power of an n-quasi-m-isometric operator is also an n-quasi-m-isometric operator. In general the converse is not true. However, we prove that if T r and T r+1 are n-quasi-m-isometries for a positive integer r, then T is an n-quasi-m-isometric operator. We study the sum of an n-quasi-m-isometric operator with a nilpotent operator. We also study the product and tensor product of two n-quasi-misometries. Further, we define n-quasi strict m-isometric operators and prove their basic properties.
Mathematics Subject Classification (2010). Primary 47B99; Secondary 47A05.Keywords. m-isometry, strict m-isometry, n-quasi-m-isometry.