diff --git a/config/config.go b/config/config.go
index 15bd87a..76e8846 100644
--- a/config/config.go
+++ b/config/config.go
@@ -23,6 +23,14 @@ type Config struct {
 	}
 	Date struct {
 		MinuteGranularity int // Restricts the minutes on which office hours can start and end to multiples of it.
+		EarliestStartTime struct {
+			Hour   int
+			Minute int
+		}
+		LatestStartTime struct {
+			Hour   int
+			Minute int
+		}
 	}
 	Request struct {
 		SecretLength int // Length of the secret token for requests
@@ -86,6 +94,26 @@ func validateConfig(conf *Config) error {
 		err = fmt.Errorf("Validating config: Minute granularity must be between 1 and 60, but is %d.", conf.Date.MinuteGranularity)
 		log.Println(err.Error())
 	}
+	if !(conf.Date.EarliestStartTime.Hour >= 0 && conf.Date.EarliestStartTime.Hour <= 23) {
+		err = fmt.Errorf("Validating config: Earliest start time hour must be between 0 and 23, but is %d.", conf.Date.EarliestStartTime.Hour)
+		log.Println(err.Error())
+	}
+	if !(conf.Date.EarliestStartTime.Minute >= 0 && conf.Date.EarliestStartTime.Minute <= 60) {
+		err = fmt.Errorf("Validating config: Earliest start time minute must be between 0 and 60, but is %d.", conf.Date.EarliestStartTime.Minute)
+		log.Println(err.Error())
+	}
+	if !(conf.Date.LatestStartTime.Hour >= 0 && conf.Date.LatestStartTime.Hour <= 23) {
+		err = fmt.Errorf("Validating config: Latest start time hour must be between 0 and 23, but is %d.", conf.Date.LatestStartTime.Hour)
+		log.Println(err.Error())
+	}
+	if !(conf.Date.LatestStartTime.Minute >= 0 && conf.Date.LatestStartTime.Minute <= 60) {
+		err = fmt.Errorf("Validating config: Latest start time minute must be between 0 and 60, but is %d.", conf.Date.LatestStartTime.Minute)
+		log.Println(err.Error())
+	}
+	if !(conf.Date.EarliestStartTime.Hour < conf.Date.LatestStartTime.Hour || (conf.Date.EarliestStartTime.Hour == conf.Date.LatestStartTime.Hour && conf.Date.EarliestStartTime.Minute < conf.Date.LatestStartTime.Minute)) {
+		err = fmt.Errorf("Validating config: Latest start time minute must be after earliest start time.")
+		log.Println(err.Error())
+	}
 	if !(conf.Request.SecretLength >= 5 && conf.Request.SecretLength <= 50) {
 		err = fmt.Errorf("Validating config: Requests' secret length must be between 5 and 50, but is %d.", conf.Request.SecretLength)
 		log.Println(err.Error())
diff --git a/config/config.json b/config/config.json
index b96993d..40b1bb3 100644
--- a/config/config.json
+++ b/config/config.json
@@ -6,7 +6,15 @@
 		"domain": "localhost:8080"
 	},
 	"date": {
-		"minuteGranularity": 5
+		"minuteGranularity": 5,
+		"earliestStartTime": {
+			"hour" : 8,
+			"minute" : 0
+		},
+		"latestStartTime": {
+			"hour" : 20,
+			"minute" : 0
+		}
 	},
 	"request": {
 		"secretLength": 15
diff --git a/controllers/addOfficeHourHandler.go b/controllers/addOfficeHourHandler.go
index e358cc8..0025ac2 100644
--- a/controllers/addOfficeHourHandler.go
+++ b/controllers/addOfficeHourHandler.go
@@ -16,16 +16,24 @@ type maskData struct {
 	Courses           []models.Course
 	Rooms             []models.Room
 	MinuteGranularity int
-	SelectedCourse    int
-	SelectedRoom      int
-	Date              models.Date
-	Duration          int
-	Roomname          string
-	Name              string
-	Email             string
-	Info              string
-	Errors            []string
-	Config            config.Config
+	EarliestStartTime struct {
+		Hour   int
+		Minute int
+	}
+	LatestStartTime struct {
+		Hour   int
+		Minute int
+	}
+	SelectedCourse int
+	SelectedRoom   int
+	Date           models.Date
+	Duration       int
+	Roomname       string
+	Name           string
+	Email          string
+	Info           string
+	Errors         []string
+	Config         config.Config
 }
 
 // Offer a form to add office hours and validate its input on receiving.
@@ -81,8 +89,11 @@ func (b *BaseHandler) AddOfficeHourHandler(w http.ResponseWriter, req *http.Requ
 		if err != nil {
 			errors = append(errors, "Die Stunde muss eine ganze Zahl sein.")
 		}
-		if !(hour >= 8 && hour <= 17) {
-			errors = append(errors, fmt.Sprintf("Sprechstunden müssen zwischen 08:00 Uhr und 17:%d starten.", 60-b.config.Date.MinuteGranularity))
+		if !(hour > b.config.Date.EarliestStartTime.Hour || (hour == b.config.Date.EarliestStartTime.Hour && minute >= b.config.Date.EarliestStartTime.Minute)) {
+			errors = append(errors, fmt.Sprintf("Sprechstunden müssen nach %02d:%02d Uhr starten.", b.config.Date.EarliestStartTime.Hour, b.config.Date.EarliestStartTime.Minute))
+		}
+		if !(hour < b.config.Date.LatestStartTime.Hour || (hour == b.config.Date.LatestStartTime.Hour && minute <= b.config.Date.LatestStartTime.Minute)) {
+			errors = append(errors, fmt.Sprintf("Sprechstunden müssen vor %02d:%02d Uhr starten.", b.config.Date.LatestStartTime.Hour, b.config.Date.LatestStartTime.Minute))
 		}
 		minute, err = strconv.Atoi(time[1])
 		if err != nil {
@@ -132,6 +143,8 @@ func (b *BaseHandler) AddOfficeHourHandler(w http.ResponseWriter, req *http.Requ
 			courses,
 			rooms,
 			b.config.Date.MinuteGranularity,
+			b.config.Date.EarliestStartTime,
+			b.config.Date.LatestStartTime,
 			courseid,
 			roomid,
 			date,
diff --git a/templating/templates/addMask.html b/templating/templates/addMask.html
index de74138..7864090 100644
--- a/templating/templates/addMask.html
+++ b/templating/templates/addMask.html
@@ -24,7 +24,7 @@
     <option value="3"{{if eq 3 $.Date.Day}} selected{{end}}>Donnerstag</option>
     <option value="4"{{if eq 4 $.Date.Day}} selected{{end}}>Freitag</option>
   </select><br>
-  <label for="startzeit">Startzeit</label>: <input type="time" name="startzeit" id="startzeit" min="08:00" max="17:30" {{if gt $.Date.Hour 7}}value="{{printf "%02d" $.Date.Hour}}:{{printf "%02d" $.Date.Minute}}"{{end}} required><br>
+  <label for="startzeit">Startzeit</label>: <input type="time" name="startzeit" id="startzeit" min="{{printf "%02d" .EarliestStartTime.Hour}}:{{printf "%02d" .EarliestStartTime.Minute}}" max="{{printf "%02d" .LatestStartTime.Hour}}:{{printf "%02d" .LatestStartTime.Minute}}" {{if ge $.Date.Hour .EarliestStartTime.Hour}}value="{{printf "%02d" $.Date.Hour}}:{{printf "%02d" $.Date.Minute}}"{{end}} required><br>
   <label for="dauer">Dauer in Minuten</label>: <input name="dauer" id="dauer" type="number" min="{{.MinuteGranularity}}" max="120" step="{{.MinuteGranularity}}" value="{{.Duration}}" required><br>
   <label for="raum">Raum</label>:
   <select name="raum" id="raum">