diff --git a/projects/resettlement-passport-and-delius/src/integrationTest/kotlin/uk/gov/justice/digital/hmpps/CreateAppointmentIntTests.kt b/projects/resettlement-passport-and-delius/src/integrationTest/kotlin/uk/gov/justice/digital/hmpps/CreateAppointmentIntTests.kt
index 7094cb24f4..2e6bd95989 100644
--- a/projects/resettlement-passport-and-delius/src/integrationTest/kotlin/uk/gov/justice/digital/hmpps/CreateAppointmentIntTests.kt
+++ b/projects/resettlement-passport-and-delius/src/integrationTest/kotlin/uk/gov/justice/digital/hmpps/CreateAppointmentIntTests.kt
@@ -18,6 +18,7 @@ import uk.gov.justice.digital.hmpps.entity.AppointmentRepository
 import uk.gov.justice.digital.hmpps.test.CustomMatchers.isCloseTo
 import uk.gov.justice.digital.hmpps.test.MockMvcExtensions.withJson
 import uk.gov.justice.digital.hmpps.test.MockMvcExtensions.withToken
+import java.time.Duration
 import java.time.ZonedDateTime
 
 @AutoConfigureMockMvc
@@ -41,7 +42,7 @@ internal class CreateAppointmentIntTests {
                     CreateAppointment(
                         CreateAppointment.Type.Accommodation,
                         ZonedDateTime.now().plusDays(1),
-                        ZonedDateTime.now().plusDays(1)
+                        Duration.ofMinutes(30)
                     )
                 )
         ).andExpect(MockMvcResultMatchers.status().isNotFound)
@@ -54,7 +55,7 @@ internal class CreateAppointmentIntTests {
             post("/appointments/${PersonGenerator.CREATE_APPOINTMENT.crn}")
                 .withToken()
                 .withJson(
-                    CreateAppointment(CreateAppointment.Type.Health, start, start.plusMinutes(30))
+                    CreateAppointment(CreateAppointment.Type.Health, start, Duration.ofMinutes(30))
                 )
         ).andExpect(MockMvcResultMatchers.status().isConflict)
     }
@@ -66,7 +67,7 @@ internal class CreateAppointmentIntTests {
             post("/appointments/${PersonGenerator.CREATE_APPOINTMENT.crn}")
                 .withToken()
                 .withJson(
-                    CreateAppointment(CreateAppointment.Type.Finance, start, start.minusSeconds(1))
+                    CreateAppointment(CreateAppointment.Type.Finance, start, Duration.ofMinutes(-1))
                 )
         ).andExpect(MockMvcResultMatchers.status().isBadRequest)
     }
@@ -76,7 +77,7 @@ internal class CreateAppointmentIntTests {
         val person = PersonGenerator.CREATE_APPOINTMENT
         val start = ZonedDateTime.now().plusDays(1)
         val notes = "Resettlement Passport Notes"
-        val create = CreateAppointment(CreateAppointment.Type.SkillsAndWork, start, start.plusHours(1), notes)
+        val create = CreateAppointment(CreateAppointment.Type.SkillsAndWork, start, Duration.ofHours(1), notes)
 
         mockMvc.perform(
             post("/appointments/${person.crn}")
diff --git a/projects/resettlement-passport-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/api/model/Appointment.kt b/projects/resettlement-passport-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/api/model/Appointment.kt
index 407cf441d5..91270d061d 100644
--- a/projects/resettlement-passport-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/api/model/Appointment.kt
+++ b/projects/resettlement-passport-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/api/model/Appointment.kt
@@ -1,11 +1,13 @@
 package uk.gov.justice.digital.hmpps.api.model
 
+import io.swagger.v3.oas.annotations.media.Schema
 import java.time.Duration
 import java.time.ZonedDateTime
 
 data class Appointment(
     val type: Type,
     val dateTime: ZonedDateTime,
+    @Schema(type = "string", format = "duration")
     val duration: Duration,
     val staff: Staff,
     val location: Location?,
diff --git a/projects/resettlement-passport-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/api/model/CreateAppointment.kt b/projects/resettlement-passport-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/api/model/CreateAppointment.kt
index 8f8a604127..619e380963 100644
--- a/projects/resettlement-passport-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/api/model/CreateAppointment.kt
+++ b/projects/resettlement-passport-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/api/model/CreateAppointment.kt
@@ -1,19 +1,25 @@
 package uk.gov.justice.digital.hmpps.api.model
 
 import com.fasterxml.jackson.annotation.JsonIgnore
+import io.swagger.v3.oas.annotations.media.Schema
+import java.time.Duration
 import java.time.ZonedDateTime
 import java.util.*
 
 data class CreateAppointment(
     val type: Type,
     val start: ZonedDateTime,
-    val end: ZonedDateTime,
+    @Schema(type = "string", format = "duration")
+    val duration: Duration,
     val notes: String? = null,
     val uuid: UUID = UUID.randomUUID()
 ) {
     @JsonIgnore
     val urn = URN_PREFIX + uuid
 
+    @JsonIgnore
+    val end: ZonedDateTime = start.plus(duration)
+
     enum class Type(val code: String) {
         Accommodation("RP1"),
         ThinkingAndBehaviour("RP2"),
diff --git a/projects/resettlement-passport-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/service/AppointmentService.kt b/projects/resettlement-passport-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/service/AppointmentService.kt
index 0769742eab..ca1e04e0ae 100644
--- a/projects/resettlement-passport-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/service/AppointmentService.kt
+++ b/projects/resettlement-passport-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/service/AppointmentService.kt
@@ -72,7 +72,8 @@ class AppointmentService(
         personId: Long,
         createAppointment: CreateAppointment
     ) {
-        if (!createAppointment.start.isBefore(createAppointment.end)) {
+
+        if (createAppointment.duration.isNegative) {
             throw ResponseStatusException(HttpStatus.BAD_REQUEST, "Appointment end time cannot be before start time.")
         }
         if (createAppointment.start.isAfter(ZonedDateTime.now()) && appointmentRepository.appointmentClashes(