diff --git a/osg-comanage-project-usermap.py b/osg-comanage-project-usermap.py
index 22fa725..879a255 100755
--- a/osg-comanage-project-usermap.py
+++ b/osg-comanage-project-usermap.py
@@ -12,6 +12,9 @@
 SCRIPT = os.path.basename(__file__)
 ENDPOINT = "https://registry-test.cilogon.org/registry/"
 OSG_CO_ID = 8
+MINTIMEOUT = 5
+MAXTIMEOUT = 625
+TIMEOUTMULTIPLE = 5
 
 
 _usage = f"""\
@@ -26,6 +29,8 @@
                         (default = {ENDPOINT})
   -o outfile          specify output file (default: write to stdout)
   -g filter_group     filter users by group name (eg, 'ap1-login')
+  -t minTimeout       set minimum timeout, in seconds, for API call (default to {MINTIMEOUT})
+  -T maxTimeout       set maximum timeout, in seconds, for API call (default to {MAXTIMEOUT})
   -h                  display this help text
 
 PASS for USER is taken from the first of:
@@ -50,6 +55,8 @@ class Options:
     outfile = None
     authstr = None
     filtergrp = None
+    min_timeout = MINTIMEOUT
+    max_timeout = MAXTIMEOUT
 
 
 options = Options()
@@ -87,8 +94,20 @@ def mkrequest(target, **kw):
 
 def call_api(target, **kw):
     req = mkrequest(target, **kw)
-    resp = urllib.request.urlopen(req)
-    payload = resp.read()
+    trying = True
+    currentTimeout = options.min_timeout
+    while trying:
+        try:
+            resp = urllib.request.urlopen(req, timeout=currentTimeout)
+            payload = resp.read()
+            trying = False
+        except urllib.error.URLError as exception:
+            if (currentTimeout < options.max_timeout):
+                currentTimeout *= TIMEOUTMULTIPLE
+            else:
+                sys.exit(f"Exception raised after maximum timeout {options.max_timeout} seconds reached. "
+                         + f"Exception reason: {exception.reason}.\n Request: {req.full_url}")
+    
     return json.loads(payload) if payload else None
 
 
@@ -147,7 +166,7 @@ def get_co_person_osguser(pid):
 
 def parse_options(args):
     try:
-        ops, args = getopt.getopt(args, 'u:c:d:f:g:e:o:h')
+        ops, args = getopt.getopt(args, 'u:c:d:f:g:e:o:t:T:h')
     except getopt.GetoptError:
         usage()
 
@@ -159,13 +178,15 @@ def parse_options(args):
 
     for op, arg in ops:
         if op == '-h': usage()
-        if op == '-u': options.user      = arg
-        if op == '-c': options.osg_co_id = int(arg)
-        if op == '-d': passfd            = int(arg)
-        if op == '-f': passfile          = arg
-        if op == '-e': options.endpoint  = arg
-        if op == '-o': options.outfile   = arg
-        if op == '-g': options.filtergrp = arg
+        if op == '-u': options.user       = arg
+        if op == '-c': options.osg_co_id  = int(arg)
+        if op == '-d': passfd             = int(arg)
+        if op == '-f': passfile           = arg
+        if op == '-e': options.endpoint   = arg
+        if op == '-o': options.outfile    = arg
+        if op == '-g': options.filtergrp  = arg
+        if op == '-t': options.min_timeout = float(arg)
+        if op == '-T': options.max_timeout = float(arg)
 
     user, passwd = getpw(options.user, passfd, passfile)
     options.authstr = mkauthstr(user, passwd)