We define modified Li coefficients, called τ -Li coefficients for a very broad class S (σ 0 , σ 1 ) of L-functions that contains the Selberg class, the class of all automorphic L-functions and the Rankin-Selberg L-functions, as well as products of suitable shifts of those functions. We prove the generalized Li criterion for zero-free regions of functions belonging to the class S (σ 0 , σ 1 ), derive an arithmetic formula for the computation of τ -Li coefficients and conduct numerical investigation of τ -Li coefficients for a certain product of shifts of the Riemann zeta function. .fi (A.-M. Ernvall-Hytönen), almasa@pmf.unsa.ba (A. Odžak), lejlas@pmf.unsa.ba (L. Smajlović), medina.susic@pmf.unsa.ba (M. Sušić).