The influence of temperature and strain rate on the type and nature of serrations observed during tensile tests in a 15Cr–15Ni–2.2Mo–Ti modified austenitic stainless steel was investigated. Tensile tests were conducted in the temperature range 300–1023 K and in the strain rate range 6.3×10⁻⁵ s⁻¹ to 1.26×10⁻² s⁻¹. Different types of serrations were found to occur in a systematic way within well-defined regimes of temperature and strain rate. A new arch type of serration and a pseudo-neck were observed and the possible mechanism responsible is discussed. A map in the reciprocal temperature-strain rate space which delineates the different regimes of serrated flow is presented.