SELECT t.Pallet,
       MAX(CASE WHEN t.RowNo=1 THEN t.Item ELSE NULL END) AS Item1,
       MAX(CASE WHEN t.RowNo=2 THEN t.Item ELSE NULL END) AS Item2,
       MAX(CASE WHEN t.RowNo=3 THEN t.Item ELSE NULL END) AS Item3,
       MAX(CASE WHEN t.RowNo=4 THEN t.Item ELSE NULL END) AS Item4,
       MAX(CASE WHEN t.RowNo=5 THEN t.Item ELSE NULL END) AS Item5
FROM
(SELECT ROW_NUMBER() OVER(PARTITION BY Pallet ORDER BY Item) AS RowNo,
Pallet,Item
FROM Table)t
GROUP BY t.Pallet

CREATE table #table
(
Pallet varchar(20),
Item varchar(20)
)

INSERT INTo #table
SELECT 'Pallet1','ItemA1'
UNION ALL
SELECT 'Pallet1', 'ItemB1'
UNION ALL
SELECT 'Pallet1', 'ItemC1'
UNION ALL
SELECT 'Pallet1', 'ItemD1'
UNION ALL
SELECT 'Pallet1', 'ItemE1'
UNION ALL
SELECT 'Pallet2', 'ItemA2'
UNION ALL
SELECT 'Pallet2', 'ItemB2'
UNION ALL
SELECT 'Pallet2', 'ItemC2'
UNION ALL
SELECT 'Pallet2', 'ItemD2'


DECLARE @IDlist varchar(1000),@Sql varchar(max)
SELECT @IDlist =REPLACE(LEFT(il.idlist,LEN(il.idlist)-1),',','],[')
FROM
(
SELECT DISTINCT CAST(t.RowNo AS varchar(4)) + ','
from(
SELECT ROW_NUMBER() OVER(PARTITION BY Pallet ORDER BY Item) AS RowNo,
Pallet,Item
FROM #table)t
FOR XML PATH('')
)il(idlist)

SET @Sql='SELECT 
* FROM
(SELECT ROW_NUMBER() OVER(PARTITION BY Pallet ORDER BY Item) AS RowNo,
Pallet,Item
FROM #table)m
PIVOT (MAX(Item) FOR RowNo IN ([' + @IDlist + ']))p'

EXEC (@Sql)