diff --git a/backend/service/ical/icalFileGeneration.go b/backend/service/ical/icalFileGeneration.go
index 47f41d9..833b44d 100644
--- a/backend/service/ical/icalFileGeneration.go
+++ b/backend/service/ical/icalFileGeneration.go
@@ -4,6 +4,7 @@ import (
 	"htwkalender/model"
 	"htwkalender/service/functions"
 	"htwkalender/service/names"
+	"strconv"
 	"time"
 
 	"github.com/jordic/goics"
@@ -20,21 +21,30 @@ func (icalModel IcalModel) EmitICal() goics.Componenter {
 	europeTime, _ := time.LoadLocation("Europe/Berlin")
 	c := goics.NewComponent()
 	c.SetType("VCALENDAR")
+	// PRODID is required by the standard
+	c.AddProperty("PRODID", "-//HTWK Kalender//htwkalender.de//DE")
+
 	c.AddProperty("VERSION", "2.0")
-	c.AddProperty("CALSCAL", "GREGORIAN")
-	c.AddProperty("TZID", "Europe/Berlin")
+	c.AddProperty("CALSCALE", "GREGORIAN")
+	c.AddProperty("TZID", "EUROPE/BERLIN")
 	c.AddProperty("X-WR-CALNAME", "HTWK Kalender")
-	c.AddProperty("X-WR-TIMEZONE", "Europe/Berlin")
-	c.AddProperty("X-LIC-LOCATION", "Europe/Berlin")
-	for _, event := range icalModel.Events {
+	c.AddProperty("X-WR-TIMEZONE", "EUROPE/BERLIN")
+	c.AddProperty("X-LIC-LOCATION", "EUROPE/BERLIN")
+	//add v time zone
+	icalModel.vtimezone(c)
+
+	var timeStamp = time.Now().Local().In(europeTime).Format("20060102T150405")
+
+	for i, event := range icalModel.Events {
 		mapEntry, mappingFound := icalModel.Mapping[event.UUID]
 
 		s := goics.NewComponent()
 		s.SetType("VEVENT")
-		k, v := goics.FormatDateTime("DTEND;TZID=Europe/Berlin", event.End.Time().Local().In(europeTime))
-		s.AddProperty(k, v)
-		k, v = goics.FormatDateTime("DTSTART;TZID=Europe/Berlin", event.Start.Time().Local().In(europeTime))
-		s.AddProperty(k, v)
+
+		s.AddProperty(goics.FormatDateTime("DTSTAMP", time.Now().Local().In(europeTime)))
+		s.AddProperty("UID", strconv.FormatInt(int64(i), 16)+"-"+timeStamp+"@htwkalender.de")
+		s.AddProperty(goics.FormatDateTime("DTEND", event.End.Time().Local().In(europeTime)))
+		s.AddProperty(goics.FormatDateTime("DTSTART", event.Start.Time().Local().In(europeTime)))
 
 		if mappingFound {
 			addPropertyIfNotEmpty(s, "SUMMARY", replaceNameIfUserDefined(&event, mapEntry))
@@ -50,6 +60,45 @@ func (icalModel IcalModel) EmitICal() goics.Componenter {
 	return c
 }
 
+func (icalModel IcalModel) vtimezone(c *goics.Component) {
+	tz := goics.NewComponent()
+	tz.SetType("VTIMEZONE")
+	tz.AddProperty("TZID", "EUROPE/BERLIN")
+	tz.AddProperty("X-LIC-LOCATION", "EUROPE/BERLIN")
+	//add standard time
+	icalModel.standard(tz)
+	//add daylight time
+	icalModel.daylight(tz)
+
+	c.AddComponent(tz)
+}
+
+func (icalModel IcalModel) standard(tz *goics.Component) {
+	st := NewHtwkalenderComponent()
+	st.SetType("STANDARD")
+	st.AddProperty("DTSTART", "19701025T030000")
+	st.AddProperty("RRULE", "FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU")
+
+	st.AddProperty("TZOFFSETFROM", "+0200")
+	st.AddProperty("TZOFFSETTO", "+0100")
+	st.AddProperty("TZNAME", "CET")
+	tz.AddComponent(st)
+}
+
+// create an override for goics component function Write
+// to add the RRULE property
+
+func (icalModel IcalModel) daylight(tz *goics.Component) {
+	dt := NewHtwkalenderComponent()
+	dt.SetType("DAYLIGHT")
+	dt.AddProperty("DTSTART", "19700329T020000")
+	dt.AddProperty("TZOFFSETFROM", "+0100")
+	dt.AddProperty("TZOFFSETTO", "+0200")
+	dt.AddProperty("TZNAME", "CEST")
+	dt.AddProperty("RRULE", "FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU")
+	tz.AddComponent(dt)
+}
+
 // if reminder is specified in the configuration for this event, an alarm will be added to the event
 func addAlarmIfSpecified(s *goics.Component, event model.Event, mapping model.FeedCollection) {
 	if mapping.Reminder {
diff --git a/backend/service/ical/icsComponenter.go b/backend/service/ical/icsComponenter.go
new file mode 100644
index 0000000..b44c74a
--- /dev/null
+++ b/backend/service/ical/icsComponenter.go
@@ -0,0 +1,46 @@
+package ical
+
+import (
+	"github.com/jordic/goics"
+	"sort"
+	"strings"
+)
+
+type HtwkalenderComponent struct {
+	*goics.Component
+}
+
+func NewHtwkalenderComponent() *HtwkalenderComponent {
+	return &HtwkalenderComponent{
+		Component: goics.NewComponent(),
+	}
+}
+
+// Writes the component to the Writer
+func (c *HtwkalenderComponent) Write(w *goics.ICalEncode) {
+	w.WriteLine("BEGIN:" + c.Tipo + goics.CRLF)
+
+	// Iterate over component properties
+	var keys []string
+	for k := range c.Properties {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+	for _, key := range keys {
+		vals := c.Properties[key]
+		for _, val := range vals {
+			w.WriteLine(WriteStringField(key, val))
+		}
+	}
+
+	for _, xc := range c.Elements {
+		xc.Write(w)
+	}
+
+	w.WriteLine("END:" + c.Tipo + goics.CRLF)
+}
+
+// WriteStringField UID:asdfasdfаs@dfasdf.com
+func WriteStringField(key string, val string) string {
+	return strings.ToUpper(key) + ":" + (val) + goics.CRLF
+}