In order to ensure safe operation of hydrogen storage cylinders under adverse conditions, one should beable to predict the extremities under which these cylinders are capable of operating without failingcatastrophically. It is therefore necessary to develop a comprehensive model which can predict thebehavior and failure of composite storage cylinders when subjected to various types of loading conditionsand operating environments. In the present work, a finite element model has been developed to analyzecomposite hydrogen storage cylinders subjected to transient localized thermal loads and internal pressure.The composite cylinder consists of an aluminum liner that serves as a hydrogen gas permeation barrier. Afilament-wound, carbon/epoxy composite laminate placed over the liner provides the desired load bearingcapacity. A glass/epoxy layer or other material is placed over the carbon/epoxy laminate to providedamage resistance for the carbon/epoxy laminates. A doubly curved composite shell element accountingfor transverse shear deformation and geometric nonlinearity is used. A temperature dependent materialmodel has been developed and implemented in ABAQUS using user subroutine. A failure model basedon Hashin's failure theory is used to predict the various types of failure in the cylinder. A progressivedamage model has also been implemented to account for reduction in modulus due to failure. Asublaminate model has been developed to save computational time and reduce the complications in theanalysis. A numerical study is conducted to analyze a typical hydrogen storage cylinder and possiblefailure trends due to localized thermal loading and internal pressure is presented. KEYWORDS: composite cylinder, transient thermal loads, finite element analysis, progressive damage *Author for Correspondence: K. Chandrashekhara, Professor, Department of Mechanical and AerospaceEngineering, University of Missouri-Rolla, MO 65409. E-mail: chandra@umr.edu, Phone: 573-341-4587,Fax: 573-341-6899.